I found Tachyon standing by the corner leading to my grandmother's house.
"What are you doing out here?" I asked.
"You were taking too long," she replied simply. "Besides, while I agreed to let you go back then, I had no way of knowing how long your 'long story' would actually be. I despise waiting, you see. I prefer things to be right there when I arrive. Do you follow?"
I gave her a weary nod. I didn't have the mental energy left for a debate. That visit with my grandmother had left my head in a spin—she had unearthed a dull ache in my chest I thought I'd finally managed to bury. I let out a heavy sigh.
Tachyon looked at me, her expression shifting to one of concern.
"So, how was the old woman? I don't think I've ever encountered someone so uniquely... unpleasant. I'd always been under the impression that the elderly were generally cheerful. At least, my own grandparents were. Though... perhaps that's a specific mask they only wear for their own flesh and blood? No, that can't be it. Even the stereotypical aunties in Osaka hand out candy with a smile. Which leads to the logical conclusion that her internal wiring has simply come loose with age. Perk up, Trainer-kun. Slumping like that doesn't suit you. A grown man coming home depressed because he lost a bout with a senile old lady? Honestly. Here, take my hand. Mental instability interferes with our experiments, after all."
Her attempt at encouragement almost worked, but I was still too unsettled to fully recover. I looked at her, hovering somewhere between gratitude and confusion.
"Don't let her get to you," Tachyon said, stepping closer. "Ask anyone, and they'll tell you there are people like that everywhere. For some, those people are their own parents or grandparents. You should be glad that isn't the case for you. Now, come on."
I took the hand she offered, and we began to walk. It took us fifteen minutes to reach the fishmonger with the "Bargain Sale" posters plastered out front. From there, we doubled back, crossed a few intersections, brushed past a handful of strangers, and finally made it back to the house.
As we stepped inside, an indescribable warmth enveloped us. The house didn't have any sophisticated climate control, yet it felt warmer than any high-end heater could ever manage. We slid the door open and shuffled into the main room. Everything looked exactly as it had an hour ago.
Seeing our noses bright red from the cold, Kosuke and the others immediately told us to get into the kotatsu. We washed our arms first, then hurriedly tucked our legs under the quilted table.
Through all of this, Tachyon refused to leave my side. She had been clingy since we arrived at the house, clearly uneasy in the unfamiliar environment, but today it was even more pronounced. When I sat down on the long side of the rectangular table next to my brother, Tachyon tried to squeeze into the same side—even though there wasn't nearly enough room for three people.
"Why are you sticking to me like glue?" I asked.
She gave a playful, mischievous giggle. "No particular reason. Don't we all have days like this?"
I couldn't fathom what had caused this shift in her mood. I tried to nudge her over to give myself some breathing room, but she resisted with surprising tenacity. Watching us, Kosuke finally gave up with a sigh.
"Fine, fine, just scoot over," he said, yielding his spot to move to the shorter end of the table.
The rest of the day passed much like the one before, but when it came time for bed, Tachyon insisted we share a futon from the start. She simply wouldn't let go.
"Tachyon..." I groaned.
The lights were still on as Kosuke finished laying out the bedding. I stared at Tachyon's face, inches from mine, and muttered, "You're a bit too close, you know."
"Am I?" she replied innocently.
"Yeah, yeah, get a room!" Kosuke teased from nearby.
"Be quiet!" I snapped at him before turning back to her. "...Listen, Tachyon. Like I said yesterday, I'm not your father. I get that you're lonely, but it's not right to cling to a member of the opposite sex like this when we aren't... well, you know."
I felt pathetic even saying it, but I was completely overwhelmed by the shimmering intensity in her eyes.
"It isn't for you to decide what is 'right,'" she countered. "I make the rules. Specifically, your rules fall under my jurisdiction. You made a vow when we signed our contract, didn't you?"
"I most certainly did not say that."
"Lights out!" Kosuke announced, clicking the switch twice and plunging the room into darkness.
"Wait," Tachyon called out into the dark. "If it isn't too much trouble for your brother, I'd like to talk with the Trainer a bit longer. Would that be alright?"
"Yeah, sure," Kosuke's muffled voice replied.
"Then... could we leave the nightlight on?"
There was a pause. "Fine," Kosuke said. He pulled the cord, and a dim, orange glow filled the room.
"Thank you," Tachyon whispered.
"You're getting pretty comfortable in this house, aren't you?" I noted.
"How so?"
"When we first got here, you looked like you wouldn't dream of speaking to Kosuke. Now you're making special requests. You've come a long way."
"Hmm," Tachyon hummed, watching my face. "It's hard to notice change in oneself. Actually, your brother and I became friends this morning."
"This morning?"
"Yes. Or did you know? ...Hey, Kosuke-kun. Is it alright if I tell him about this morning?"
A muffled "Go ahead" came from under the blankets.
"He says it's fine. So, I'll tell you: your little brother has a girlfriend. A perfectly charming girl, from the look of her."
"What?! He actually got a girlfriend? For real?"