James
In James' defense, he hadn't been paying attention- or, well, he's never really paying attention. James doesn't think he's given any thing his undivided and complete attention in years, his mind was always wandering away and replaying funny moments from the day before or a Tiktok that he'd watched, it had been happening since he was little, and it only gets worse the longer Regulus isn't around, each U-turn he made to go back to the house because he forgot something making him grow less and less focused, hell, he'd be happy if he could remember where the hospital is.
Eventually, he did make it to the hospital, walking down the hallway he'd come to recognize as Regulus' and going over to room 39-A, pushing the door open he saw Regulus laying on his bed, a small tray of food in his lap, Regulus stared down at it, like if he looked at it long enough he'd feel less sickened by the thought of it, Which never worked. James leaned against the doorway, watching Regulus pick at the food, before clearing his throat.
Regulus' head shot up, he looked startled but that faded once he saw James, "Baby," James said from the doorway, "What's wrong, hon? Is it getting bad again?" James asked, worry lacing his every word, he'd never understood why Regulus didn't like eating in front of people, he'd never understood why Regulus had that little voice in his brain, just like Regulus never understood how James saw shapes and colors when he listened to music. and they didn't really need to, the both of them could help, love, and support each other without needing to understand what the other person is going through thouroughly, so long as they communicate what they need.