he’d sent me an incredibly difficult equation from some kind of advanced university paper as a challenge. I’d solved it just to spite him, and dug through all the papers available online to find something even trickier, and sent that back. We’d then fallen into the habit of exchanging questions every morning. We never said anything else. Just the screenshot and the answer. One blow traded for another. He would respond each time without fail, and we’d kept it up all the way until school started again.
