Oh boy, honestly whenever anyone asks me this question I ALWAYS without fail: blank. Im positive I have plenty. Like Jason being the romantic in the relationship. But anytime I answer this question I always forget 90% of them. I also am guilty of not fully committing to my own HCs. Like I think of one and then ignore it in my art HAHA
but off the top of my head, I do like to think of both of them as being differing degrees of Demisexual & Demiromantic. Like I see Jason strongly in both. He feels absolutely nothing for anyone until he feels that emotional attachment. But he's also longing and starving for That Romance from his Novels(TM). So, when he starts falling he falls HARD. While in contrast, Tim is very demisexual and the type to compartmentalize his emotions for later. Or just someone very uncomfortable with affection. The kind of person to squirm from a hug or crack a joke to make it less intimate. But he's low key starving for it as well. He's more uncomfortable in his longing for that while Jason wants to drown in affection the moment he gets a little taste. Hence my art where he's on his knees with Tim.
Also, I do head canon on the side that Jason, yes is a book nerd, but he never actually understood the books he read? He was just so passionate about them and his own nonsensical interpretations to them. For instance, in his early childhood he wouldn't really have anyone to help him understand these grand classics he's reading and would ask around to random people what X or Y means. In turn, they would tell him something random and he would believe it. In example, his interpretation of star crossed, might be so literal that he would think stars formed an X in the sky and that meant not even the stars wanted them together, lol. And even as an adult he would sit people down to explain, in long impassioned rants, this wild interpretation of a book that while it is incorrect, he still gets to the same general area? He's definitely on the right track. and there is still a huge childlike wonder and essence to his observations. He's deeply creative.
Anyway, that's all I can think of at the top of my head for now.
Thank you for the question, Anon! I hope you have a nice weekend. :)))