Combeferre with ADHD
Combeferre with a completely rubbish working memory who can tell you about the anatomy of moths in exhaustive detail but has to stop and think hard before he can say what he had for breakfast and needs to write down all homework assignments and other responsibilities immediately or risk forgetting them entirely.
Combeferre hyperfocusing on whatever book he’s reading and being impervious to outside distraction.
Combeferre having days when he can’t focus on anything at all and roaming through the streets because he can’t sit still and keeps noticing every single distraction around him when he tries to get anything done.
Combeferre toying with anything he can find to keep his hands busy so that he can concentrate on other things.
Combeferre with a complete inability to keep his room neat and organized.
Combeferre who got through school as a kid by being brilliant and now doesn’t know how to study and is having to cram the knowledge into his brain and feeling like a failure because he’s doing fine in his classes but he could be doing so much better if he just tried harder.
(Modern AU Combeferre finally getting an explanation for what’s wrong and it’s like a weight is lifted off his shoulders because it all makes sense now.)