In light of recent events (manga), I hc that Kuroo always watches Kenma, but keeps a closer eye on his hands, knowing how important they are in his role as setter. After practice, he would sometimes check Kenma's hands for any injuries and holds them a little tighter before letting go. But one time during their walk home, before entering his house, Kenma slowly holds Kuroo's hands and mutters, "you're not exactly subtle. Take extra care of these too, you're a middle blocker after all."
I forgot to mention this, cos I’ve kept this HC to myself, but I gotta share with a drawing cos this is one of the most beautiful and well-thought out KuroKen HC I have ever laid my eyes upon.
Thank you for telling me such a beautiful idea!