You get this feeling sometimes that you're being watched. You know... At the back of your mind... You get the sense that eyes are on you more than on other people, which makes you tuck in a loose shirt tail and check to ensure you really wiped that bit of mayonnaise off your cheek from your turkey sandwich at lunch. Then you look around.

I'd done well on my organic chem final yesterday (and by that, I mean more than just passing but certainly not anything close to an A), so I'd decided to treat myself to a day at the museum to see the dinosaur exhibit and to learn things I'd never ever be tested upon. Perhaps I'd find something that really interested me. I needed a career path to firm up my major, but a mix of classes like organic chemistry and Celtic folklore indicated I still wandered aimlessly.

Unfiltered light through a multitude of windows lit the Los Angeles Natural History Museum's dinosaur hall nicely. It was winter and late afternoon. Sunset colors tinged the sky orange and that reflected in the hall. I'd taken out my phone to snap an interesting family tableau of tyrannosaurs: an adult, a teenager, and a juvenile arranged such that I could imagine the bones clothed again in living flesh, six-inch dagger teeth flaying meat from the newly killed iguanodont lying between them. Someone in the view suddenly looked away.

I reflexively turned my back. I looked at the photo, blinking, then put my finger on it. Yes. Right there. In the Harry Potter picture, I'd caught a tall blonde staring right at me. Predator eyes, I thought, just like the set-together forward-facing eyes of the tyrannosaurs I'd been photographing. She'd seen me lift my camera too late, but she reacted, turning away.

One look at me and it's obvious I'm no varsity letterman, or much to look at beyond being average and more thin than fat. My hackles rose at the confirmation that I'd been being watched, though. I pocketed the phone and started walking, buttoning my sweater rapidly as I went. It was nearly closing time, anyway. I rushed past through the foyer, passing the "dueling dinos"—a black-boned T-rex and triceratops—that had graced the area since before I was born, down the worn stone steps of the building and into the cooling twilight. A glance back at the portico arches showed that the two women that followed me were both dark haired; neither were tall.

I turned and walked swiftly toward the Expo Line train stop. Others walked the same direction, in coats and sweaters, but none were tall or blonde. There were advantages to the regular school year: not having time to think about stupid stuff like being watched. The air felt chill and dry, mid-fifties maybe, and I grabbed the neck of my sweater to close it. Taking the back entrance to the museum would have made my walk shorter.

The street lights came on as I crossed eastbound Exposition Blvd to the median train platform and mounted the steps up. A mix of students whose last final was today, various school administration staff with loosened ties, and business types milled there. My red sweater, which wasn't a school sweater, was different enough that I caught evaluating looks.

But I knew now I was just being stupidly paranoid. I mean, a tall blonde, maybe from the Trojans volleyball team, eying me? Really? Was that a bad thing?

I'd gotten caught up in that last thought thoroughly enough that I looked up startled when the Santa Monica-bound train sounded its horn. I could hear the sound of brakes, but it still moved fast and the head lamps were dazzling. I'd stood on the yellow line and I straightened just as I caught sight of a very tall blonde, definitely volleyball middle blocker material from her sheer sinewy height. She wore a jeans dress and a no-longer cool suede leather jacket with fringe. It reminded me of my elderly aunt who sometimes wore 1960's clothes from her early twenties, because, like she said, she could. The blonde even wore amber beads. The ensemble belonged in a vintage clothing museum. She stood less than five feet away. Our eyes met. Her's were blue—the bright twilight behind me reflected into her eyes and I could tell.

And she had this expectant smile. Like she knew me. Like she expected me to maybe remember her?

But I didn't. I only recognized her from the dinosaur hall.

As the front of the train reached her, somebody shoved my hip. My face headed toward the edge of the platform and I saw the onrushing train from that specific perspective you don't want to see a moving train from. I yelled and windmilled my arms at the same instant, but, to make things worse, someone kicked my right foot from under me. Not only did I lose my balance, but I started twisting counterclockwise and falling sideways toward the tracks. People close to me reacted instantly, all, unfortunately, jumping away. In an elapsed second, I saw an expanse of black glass windshield heading for my nose.

Something significantly less hard than the slowing train struck me in the chest, at the same time making a loud thunk as a considerable mass bounced off the shell of the train car. A hand swatted the right-side of my face. As a result, I felt air rather than the glass and fiberglass of the train car whizz past my head. My right shoulder still hit the side of the train, grazing it, and it still kicked me around in a pirouette.

The next instant, I bashed into a couple of bystanders with a new weight barreling me forward, but at the same time reaching behind me. Together, we all stumbled until we hit the scheduling board at the other side of the platform. I think we may have knocked into a couple more riders, but my ear rang from being slapped away and the bruising force of the train left my shoulder stinging.

I heard, "Are you okay?" "Motherf—" "Did you see who tripped him?" "Ow!" as people parted. I slid down to the ground with my back against the plexiglass surface of the schedule board.

My arms shook and I trembled as I realized how very close I had come to dying.

What had just happened? Things like this didn't happen to me.

But they had. Someone had tried to kill me.

"A-are you all right?"

I looked up at the blonde with blue eyes. She had grabbed the lapels of my sweater to keep me from sliding over, stretching the knit material out. Her accent sounded faintly southern and cultured eastern at the same time. She'd been watching me.

Thank goodness.

The left shoulder of her fringed suede jacket was shredded and blackened.

"You saved me," I said.

"I-I—" I saw her mouth move, and maybe I heard a whisper: "I wasn't supposed to be the one to do that."

Maybe I'd heard that. Maybe. It didn't make sense, though. The ringing in my ear subsided substantially over the next minute and though I stopped trembling, I felt shaky as she and a grey-haired man helped me back up.

"Should I call 911?" the old guy asked.

I moved my shoulders. I felt the side of my face, then my ribs. I felt a bit bruised but not otherwise hurt. I did my best to smile. "No. I don't think so."

"You're going to have a big bruise on your face, son."

I laughed, and that sounded rather iffy, but, "I just need something to calm down. I'll be fine. Anyone see who shoved me?"

I had a ring of people around me, staring. Well, I now was definitely being watched. A guy in a blue flannel shirt over a white t-shirt said, "Some tall dude in a black hoodie with an attitude. Anybody video it?"

A chorus of noes, and a "Shoot. Missed it."

Another said, "Never a metro officer when you need them. Am I right?"

Soon it was only me and her. She looked inordinately concerned, examining me up and down. She was too old to be on the volleyball team. Maybe she was an assistant coach? She said with that hard to place accent, "I'm pretty sure there's a clinic or hospital near by. Are you sure you don't want to go there?"

I said, "No." I rolled my shoulders again. That would hurt tomorrow, but... Other than where she tackled me and shoved my head aside, I felt okay. I reached for her hand. Flesh had been scraped from the back of it, perhaps where she may have hit the train. And her shoulder definitely had hit the train car. "You, on the other hand..."

She looked at her hand for a space of a few heartbeats. She blinked, for an instant looking nonplused, eyes widening like she'd unwittingly shook Emma Watson's or Ariana Grande's hand. She was easily a foot taller than me, maybe more. She pulled free and said, "That won't be necessary."

I took a deep breath and said, "I'm not ready to get on the train right now. I could really use something hot to drink. Let me treat you. You saved my life, after all. I owe you."

She looked more shocked from my offer than I felt by almost getting killed by a train. I smiled and she smiled in return, nodding, before saying, "Sure. Why not. I have a few minutes to spare."

I was also interested in why she'd been following me, and what the, "I wasn't supposed to be the one," comment meant.

We walked silently. In ten minutes, we sat at a table with drinks. She'd lifted the plastic top and she inhaled the flavored steam deeply, ever so slightly shaking her nose and closing her eyes. "So this is what a Starbuck's dispensary smells like?"

Her face had gone from a pensive frown to a smile when we walked in and she'd begun breathing in the aromas, looking like that kid in a candy store I'd heard about but never seen in real life. She added, "They don't have them where—" She stopped abruptly and looked me in the eye as if she'd surprised herself. "We have caffeinated drinks—"

"Where you come from? But no coffee?"

"Yes. Coffee. Of course. Coffee. Just not..."

"Starbucks."

"Yeah."

Not many places in the U.S. where that was true. "And where is that?" An appropriate bit of small talk.

The top clicked as she shoved it back on, momentarily having trouble getting it to seal properly. "You know, I am in a hurry."

I reached out and put my hand on hers as she pushed herself up from the table. It was the one with the scrape, unfortunately, but she didn't flinch. It felt soft. Funny how nearly dying made things that seemed rude before—like being forward with a woman I didn't even know the name of—somehow feel not as inappropriate. I'd not even thought about it; I just reacted, asking her out, asking questions.

She paused.

"Sit, please."

She complied almost like she were a child, saying, "Okay." She lifted her cup and sipped, slowly getting this blissful look on her face like... like at any moment tears might have ran down her cheeks.

I rotated my untouched cup in my hands, letting it warm me. I looked down before I said, "I had this feeling—before you lunged to save me—that you knew me. You'd been following me in the museum, too, hadn't you?"

Did I sound crazy?

She hadn't said anything when I looked up to find her still drinking her coffee, now thoughtful instead of blissful. I pegged her age at over thirty. Her face seemed very elongated, like Abraham Lincoln in that famous smiling daguerreotype. She didn't look at all homely, but somehow remarkable. Stately, maybe? She definitely worked out hard. Maybe too hard, considering how I could clearly see her muscles and that didn't often happen with women, except body builders, and she wasn't bulky. Just strong. The coach idea resurfaced. I asked something safer: "What's your name?"

"Sakura Nichi," she said around the cup.

She looked Eastern European, if I had to guess, not asian. "Sounds Japanese."

"I'm not."

"I'm—"

"Carl Howard Yarza. I know," she said disconsolately, then set down her coffee almost reverently. She glanced at the palm of her hand and grimaced. Something flashed, like a cell phone, but it would have had to have been paper thin. "It's been an honor to have met you Mr. Yarza, and you have no conception why, I'm sure. I really really have to go." She stood, causing her chair to screech against the tile floor.

I stood.

She looked at me from head to toe as if trying to memorize everything she saw, then said, "I have to ask: Do you feel changed? By what happened, I mean. Did it change you?"

I blinked at the non-sequitur. "I did ask you out for coffee and did ask some questions I'd probably have thought through and not asked. And nearly dying makes some stupid stuff like not making decisions seem really stupid, like it's time to settle on a direction in my life. So, yes. Is that what you mean?"

"Good enough." With her incredibly long legs, she turned and strode outside almost at a sprint.

I grabbed her half-finished Pike's Place blend, and my unsampled latte, and dashed out after her. Because she wasn't out-right running, I caught up to her at the red light, then crossed with her, heading back toward the red brick buildings that crowded the USC campus—not, as I had expected, toward the metro rail or bus stop on the other side of the intersection. So, she hadn't been just going my direction.

She glanced back and said, "And don't mention my name in your journal, whatever you do."

I stopped as if I'd hit a wall. My journal? How many guys wrote in journals? You know. Lined paper. With a leather cover. Using a pen. None that admitted it. I'd gotten thoroughly ribbed during my senior year at Fairfax High when I mentioned it in the electronics club to someone. Somehow my picture ended up in the yearbook beside all the girls in the school who journaled, though I wasn't in their club. Probably should have been, but...

So she'd read the yearbook. Obviously. Which only meant she'd researched me. Still. Weird.

I rushed after. So, what did that make me, following her?

Now her long legs made a difference, with me trying to rush still foolishly carrying both hot cups with mine spitting drops of latte as I went. She headed in a direction with few a Friday night students heading home, and none paying attention to her in any case. She'd put a full building between us when she looked at her hand.

Yes, her hand glowed. I gotten my vision corrected with laser surgery a year ago. Her palm definitely glowed.

She suddenly darted right between buildings.

Not a second later, a tall man in a black hoodie separated from a lamp post. Tightening the draw strings of his hood with a decisive jerk, he leaned forward and rapidly followed her.

Silently.

He was dude. In a black hoodie. With an attitude. A chill ran down my spine.

Now I ran, not caring if I got coffee on me.

I didn't run away; I ran after Sakura and the dude with the attitude problem—after the dude that I suspected had tried to kill me. What was the matter with me, today? Right? I'd almost died, but Sakura had prevented that—whatever her reasons.

I stopped an instant and jabbed the blue campus police call button on the lamp post Dude had made like a chameleon beside, then followed him. I wasn't entirely stupid.

They'd entered a service way between buildings. There was a beat-up yellow painted parked campus janitorial pickup, discarded drink cans, a few trees that softened the view of the passage way from the main road, and shadows. And more shadows, especially as the walkway veered left and sloped down to a basement-level service porch. The shadows actually made me slow down. The dusk and a burnt out lamp made it hard to see where to step. It reminded me that someone could be hiding up ahead.

"Hey!" someone cried.

Sakura.

I heard a thunk and a grunt, then a clang, then things like boxes falling over. As I approached the corner cautiously, a weird glow suffused the area between the building and the one beyond. It wasn't just a glow. The light and the atmosphere caused an immediate ache in my sinuses which sent a stabbing pain to my temples. The area just ahead distorted slightly, like it had been ice and suddenly cracked. Or crystalline. Sparkles seemed to float around, not unlike from a disco ball, as if the source of the light swayed in a breeze. There were also flashes of orange and purple, and a crackle like electricity in power lines. Jumping shadows added to the instant eyestrain, and came from the two people who fought in front of... whatever it was.

I got to the corner and heard a bang followed by a man saying, "Just go through, and I won't hurt you."

"You can't be here!"

"And what are you doing here, then?"

"At this point, ensuring you don't change anything," Sakura cried and lunged.

She had grabbed a length of discarded PVC pipe, but he had a two-by-four he wielded with leather gloves. With a bang, he parried her attempt. I could see he was the better fighter as he pushed at her and tried to kick at her feet.

The glow emanated from beyond them. The air itself shimmered, but nothing like a heat mirage. It was almost as if I were looking through a quartz prism, with the scene being bent from straight ahead. The light of the recently faded sunset seemed to stream from the right, illuminating some of the distorted bricks with impossible light. To the left bricks were harshly illuminated in florescent light. The lighting slid and rotated, with occasional flashes of what looked like light from a cloudy morning; I suspected tomorrow would look much like that when the forecasted rain rolled in.

Sakura caught the swung two-by-four with her pipe, which made an ominous cracking sound as if it were about to cave in. The two both grunted as they tried to force each other towards the source of the glow. The distorted light had by this point made me queasy, and I felt an almost magnetic pulling on my right, still aching, shoulder and arm.

Sakura said, "I can't allow you—"

The man stepped back and wound up again to swing with his improvised bat.

I dashed forward and threw my latte cup at him. I'd aimed at his middle, but the hot coffee hit him in the neck.

"Yow!" he cried, inadvertently flinging the wood toward me. As I ducked, Sakura jumped at him, brought herself and her pipe between us. The man almost recovered, but I threw her coffee at point blank range when Sakura gave me an opening. He hesitated enough that Sakura knocked him off his balance. As she pushed him, I reached and gave the hooded man an additional shove, like he had me, before. Whatever the actinic light show was, I expected that our combined effort would knock him against the brick wall and the lamp that caused it.

Instead, something shattered. Not a window. These dark ones had bars on them. Nevertheless, the crackle of crystal, or glass, was manifest and ear-shattering. I felt it in my stomach, like the deep bass of a giant subwoofer. The light flicked out like switched-off LED.

The man in the black hoodie was gone. The service area, lit only by fluorescents, with scattered papers and junk and a broken wood box, looked mundane again.

"What just happened?" I asked.

Sakura looked ashen. Blood dripped from her upper lip and looked black in the bluish light. She said, "Tell me you didn't see that."

"I didn't see that," I replied.

She moaned, covering her eyes and rocking where she stood. "History can't change, which means I'm part of this history, but if I'm not and I stopped him..." She gasped. She turned and examined the wall. She looked at her palm. The skin glowed like a cell phone screen. She looked as red numbers and dots scrolled across it, then at the brick wall. On her hands and knees, she patted along the bricks where it met the cement as if looking for a lost earring. No broken light fixture. No bad dude, either. "It's gone."

"What's gone?"

"I don't know why I'm so worried. History is immutable. That's the theory. Maybe I'm supposed to be part of this—"

"History?"

"But what if I'm not?" I half expected her to say, "I am in so much trouble," but instead she added, "That I could find this discontinuity that I could use get here seemed too good to be true. To meet—". She looked at me and her eyes widened. "No, no, no, no," she said.

"No, what?"

"Hey!" some man called from the service pathway. I saw a flashlight beam. "Campus police. Who's down there?"

"Come on," I said, taking her hand when she froze up. I looked where the guy who'd tried to push me into a train had disappeared. (Disappeared!) "Where do you think you are going to go now?"

"Yeah. The discontinuity is gone," she said, as if there really had been a doorway there. The whole thing felt unreal. I wasn't going to claim to be a scientist, yet, but I'd spent enough years taking science courses to know I couldn't explain what I had seen, unless the dude had pulled some sort of slight-of-hand. And he'd seemed determined to fight, not escape.

I pulled. She followed.

The officer immediately saw her bleeding lip and ordered us apart, but it didn't take much for her to convince him that we were friends and to believe my story that she'd fallen and called for help. I was a scrawny thing compared to her. Him to her, for that matter. It seemed unlikely I could have harmed her.

In the back of the patrol car, heading to the campus clinic, she said in a low voice, "Don't write about any of this." She rubbed her shoulder. It obviously hurt. Going to the click was a good idea, even if she hadn't wanted to before.

"You seem adamant."

"You never wrote about it, which means you never should, but I can't take a chance that you will now."

"Change history?" I scoffed.

She swallowed hard. "How can I say this in a way that won't make a difference going forward? It won't ever be your area of expertise, so..."

I found myself unaccountably bristling. Unfortunately, she seemed to know a lot about my past. And maybe my future.

"There are four physical dimensions."

"Three," I corrected reflexively.

"Four. The T-axis is as physical as X, Y, and Z. Time's a crystal structure you can thoroughly examine in any direction if you know how. But like most solids, there are defects in all dimensions, inclusions and misalignments. Time and crystallography share a lot in common. There are an amazing number of discontinuities on the Cretaceous–Paleogene boundary, and billion-year ones on M—" I'd swear she'd said Mars, but her voice had faded suddenly.

"And you walked through—" I whispered "—through a crack in time?"

"A crack?" She snorted and shrugged, then jerked in pain. "Good enough."

"And you expect me to believe that?"

She blew air through her lips and looked out the passenger window. "I hope you don't."

I thought about it. About what she'd said after the fight. What she'd said in the Starbucks. As I helped her out of the car toward the clinic—with the escort of the officer because we were both obviously bruised and scuffed up, and I don't know if I'd trust us, either—I asked in a low voice, "You came here, through time I mean—"

"I stepped through an unstable discontinuity."

"To meet... me? Why?"

Sakura stopped, letting the officer walk past us. She looked down at me and whispered, "I wanted to witness that moment in your life that 'changed everything'."

"Why?" I repeated as she walked forward through the glass door the officer held open for us. "Why me?"

"Pick a philosopher, a president, and explorer. Do you think any knew what they would become before became someone important?"

"I—" I followed her inside toward the nurse at reception and felt my face twisting into an WTF expression. "Me? Important?"

"You are more than meets the eye, and the less you know the better. I sure hope history really is immutable, else I've really screwed up this time."