The following Monday, spring classes started up and I let myself fall back into my Boston rhythms—my new, fresh life where the past stayed in its place. So Principal Farghasian was a liar, too, apparently, although Aunt Amalia never specified how. What difference did that make to me?

A life I can be proud of. That's what Adam had told me we both needed to find, and that's what I had made every effort to do.

I woke up at six that Monday and headed over to campus to take a dive in the university pool. MIT had a swimming requirement for all students, something that had struck me as very odd when I had first arrived, because it seemed so arbitrary. "Why swimming?" I had asked the senior giving us the tour of campus back in August. "Why not, I don't know, archery or something?" "Because it's good for you," he had responded, an answer which seemed to satisfy everyone else on the tour.

Now I was grateful for it, as I had made it part of my morning ritual. I found my mind was clearer in the water, the effort of breathing at regular intervals, of using muscles in my shoulders I had forgotten existed, all of it bringing me into a trance-like state. Physics principles floated above my head as I made the laps, so clear I could almost touch them. Velocity and resistance. My body a machine, predictable and therefore complete.

I showered in the locker room after, placed my wet bathing suit in a sealed plastic bag, and dried my hair in the mirror. No makeup, just ChapStick. I felt rejuvenated as I headed over to my first class. And the feeling lingered as I took my seat in the middle of the huge lecture hall, the promise of the day opening up before me like a flower.

I smiled to myself as a familiar face entered from the back office and approached the podium at the front.

"Welcome to the future!" Lisa Sanchez beamed.

She laughed at her own joke, but nobody else in the lecture hall seemed to realize that she had made one. So she coughed the effort away and proceeded to read the next item on her agenda, projected larger than life onto the screen behind her.

I couldn't help but chuckle, though, remembering how warm and inviting Professor Sanchez had been when I'd met her in the spring at the El Gallo café for my in-person MIT interview. I had been hoping to find an opportunity to take one of her classes since I got here, so when I saw that she was teaching "Futurism: Smart Tech and Where We Go From Here" this semester, it seemed like fate.

"We'll spend some time at the beginning of the term talking more broadly about culture, sociology, the evolution of modern communities."

The girl next to me in the fourth row cleared her throat, and due to the cavernous design of the room, the sound reverberated off the walls and eventually came back to land in my ears a second time. Other students shuffled, and I caught a couple confused glances left and right.

"I can see some of you think you wandered into the wrong class," Lisa joked. "Don't worry, you're in the right place. But to understand where tech is going, we first have to understand why it's going there. What is technology, after all, but a society's attempts to solve communal problems?"

I jotted this down in my little blue notebook. Despite enormous social pressure to use my laptop for this purpose, I just couldn't get used to the idea of typing my notes as I went along. There was something about holding the pen in my hand, feeling the ragged flow of it across the paper, that cemented the ideas in my mind. I couldn't get the same sensation from a keyboard. Although the constant echoing click of fingers hitting keys all around informed me that I was alone in that camp.

"As the class progresses," she continued, "we'll brainstorm where we think all this tech is going. By semester's end, you'll have created a protype for your own invention. Don't worry, it doesn't have to be perfect. It's the ideas that matter at this stage."

My pen was making the looping cursive of the words ideas and stage when I felt my seat vibrate lightly beneath me. My backpack was under the chair, close enough that the phone in the front pocket could be felt. I ignored it and kept writing.

But then the vibration subsided and immediately started up again. While the class was rapt in the lecture Lisa had begun, I slid my hand down to find the phone.

M, can you come home?

It was Piper. She knew I had class this morning. She wouldn't be writing if it wasn't important. I held my breath and waited while the three gray dots blinked before me, as though the phone had to prepare itself for whatever Piper was going to say next.

It's happening again.

He's asking for you.

A gurgle of fear started bubbling in my stomach, but I swallowed it back down.

Coming now, I typed back, and then slowly nestled the phone back into the pocket. Shit. I was sitting right in the center of the long bank of seats. There was no way to do this discreetly, but it had to be done.

"Excuse me," I whispered to the confused girl who was trying to type Lisa Sanchez's words verbatim into her laptop. She twisted her whole body, computer and all, to the right so I could slide by. This prompted the twelve or so students in the rest of the row to do the same, and by the time I got to the end of the aisle, the whole hall had turned to stare.

"Was it something I said?" Lisa asked, and this time everyone seemed to realize that it was a joke. The room rumbled with a chorus of snorting chuckles.

"Sorry," I whispered. "Family thing. Sorry."

Lisa nodded and went back to her projector, cuing my newfound audience to return to their work.

I didn't realize until I was on the bus and crossing the bridge to Boston proper, where the brownstone apartment I shared with Piper and Robbie was tucked onto a tree-lined street—thanks to Piper's inheritance—that my hands were shaking terribly. I crossed my arms and tucked them each into the crook of the opposing elbow to steady them.

Technically, I wasn't supposed to live off-campus as a freshman. I should have been in a dorm. But I had gotten a special dispensation to live with my brother for medical reasons. I didn't mind it so much, except sometimes in the cafeteria when I saw groups of people hanging out, laughing, talking about the new posters they wanted to put up in their room, or a new way to lay out the beds for more study space. Not that I would ever complain, but I did wonder sometimes if I had missed a step in the whole "going to college" experience.

The bus let me off at the end of our street. A winter storm had left roughly a foot of fresh snow the night before, and while the street itself and the sidewalk had been scraped clean, the icy tendrils still clung to the bare branches above my head. The afternoon sun was now shining through those dripping fingers, creating prisms of effervescent light all around. I walked gingerly towards the apartment like I was entering Narnia.

"I'm home," I called softly as I kicked off my boots and yanked my damp knit cap off my head, leaving it in a heap on our entryway bench along with my gloves, scarf, and backpack. "Piper?"

"We're up here," she called from up the stairs.

I gulped down my hesitation and started climbing. The door to their bedroom was open, but I couldn't see them at first. It wasn't until I pushed the door back and came fully into the room that I caught sight of Robbie, crouched on the floor against the far wall.

The parallel struck me immediately—it was the exact pose he had landed on when I'd first found him again on the timeless DW train. He'd had one of his attacks then, too, throwing things and shouting, kicking at the aged wood panels of the train car over and over again until they had splintered. Then he'd collapsed onto the floor, staring vacantly ahead, a million miles away.

I crouched down next to him now. His face was flushed and red, his cheeks still wet and his nose running. Piper sat next to him, her hand resting gently on his knee, though he didn't seem to feel it.

"When did it start?" I asked her.

"An hour ago."

She was making a concerted effort to keep her face and voice calm, I could tell, but her furrowed brow made it clear that this one had really scared her. Evidence of smeared mascara was still visible beneath her almond-shaped eyes.

"Robbie?" I asked.

He just shook his head. "It won't stop this time."

"Yes, it will," I promised. "It always does. Did you take the medicine?"

He nodded, but a fresh wave of tears was forming in his haunted brown irises.

"He hasn't eaten anything," Piper declared, standing up and doing her now-I-will-make-myself-useful face. "I'll go make some soup."

"Thank you, Piper," I said, offering her a weak smile. I waited until she had left the room before shuffling my body to be a bit more comfortable by Robbie's side.

"It's never gonna stop," Robbie said quietly. I only heard him because my head was resting on his shoulder.

I was tempted to say the first thought that popped into my head: Of course it will. Think positive. But I didn't want to lie to him. Robbie was one of the smartest people I knew, probably a genius really. And he was right. It was never going to stop. Not completely.

That's not the way bipolar worked.

"She should leave me," he said now, wiping the tears off his face. "No reason she should live with this."

"I'm pretty sure that's her decision," I answered. "We love you and we're not going anywhere."

"I wasn't supposed to be like this," he said, shaking his head, and then finally burying it between his knees, which he'd pulled up to his chest.

I shook away a fresh wave of guilt. It happened every time Robbie had an episode. The endless question: Would Robbie be sick like this if he didn't remember that he'd been on the train?

In the reality that I'd created the first time I went through Yesterday, he'd had a normal childhood in Portland with our mom. He'd helped her run the hotel. He'd had lots of friends in school. Played football. And he'd had no memory of me, of our childhood together, of Kieren daring him to play chicken with the train, or, most importantly, of the three years he'd spent alone on that train before Piper had appeared and they'd fallen in love.

Three whole years. Alone.

Enough to drive anyone mad.

For a while there, it had all been erased from his mind, and I think he'd been happy. And then I went and ruined it last year by going through the Yesterday door again and changing the past—giving him back all the memories we had shared, while also leaving him to live his life in Portland.

At the time, it had seemed like the perfect compromise. He could have both that way—he could have Mom and me. We could share him.

But a human being isn't a puppy that you can split custody of after a break-up. Remembering both of his childhoods had split Robbie in two. It was simply asking too much of his brain to be divided like that.

When the doctor had first diagnosed bipolar, I'd wanted to scream at him that he was wrong. Robbie wasn't sick like that. There was nothing wrong with Robbie's brain. It was me! I had done this to him. I was the problem.

But that was before I had lived with Robbie for months, and I had seen these episodes half a dozen times. I'd finally had to concede that the doctor was right. It wasn't just the memories that were affecting Robbie; it was his brain chemistry. Something wasn't working right in that brilliant mind of his.

Would it have been that way anyway? Or was it my fault?

"I'm sorry, Robbie," I said to him now for probably the hundredth time. "I'm so sorry."

"It's not your fault," he assured me, his hand landing near mine on the floor.

"It is. I shouldn't have done it."

"I'm glad I remember. I can't imagine my life without you and Piper."

I started crying, shaking my head with self-loathing. "But you'd be healthy if—"

"No, I wouldn't," he insisted, and I could tell from the even keel to his voice that he was feeling better. Maybe the meds were kicking in. "This isn't your fault."

"What do we do now?" I asked, and I realized that I sounded seven years old again, asking my big brother for help.

"Let's just sit here for a minute, okay? I just need... I need another minute."

And so we sat there, and we stared ahead toward the opposite window, where the white ice branches were sprawling out like a network of veins towards our apartment. The day had started with such promise, I couldn't help but think. I had almost convinced myself it could stay that way. I had almost felt like Robbie and I were finally free.

After a minute, a red cardinal landed on one of the branches, alighting with such speed that it shook the clinging flakes loose, making them burst down in a shower of shattered crystals. 

****

Above: Boston at sunset. I spent a summer there once when I was 17, so excited to wake up every day in a new city, a million possibilities at my feet. 

I know it's been a tough year, so let's play a game: when the epidemic is over (bless the scientists!), what is the first place you want to go visit? For me, I'd love to show my husband Barcelona.

XO, Rebecca