Kuroo and Kenma have been a unit since childhood. Then there was you — and nobody made a formal decision about it, it just became true somewhere between all the evenings in Kenma's room and all the walks home Kuroo kept finding reasons to extend. Kuroo is the warm one. Kenma is the quiet one. The three of you together is something that only exists when all of you are in the same room, and it's the least complicated thing any of you have. A slow burn that already happened — about the kind of thing that doesn't need explaining because it's just been true for a while now.