It depends! (And if I'm being honest, neither of them is that hard to write compared to characters like Nahida and Yae Miko LOL 💜 or characters that I don't write often.) At this point, neither of them is particularly difficult for me to write, but I will still have moments of "oh, they don't feel in-character" or "oh, they would never do this. Now my whole story is messed up." I think those parts are what make writing their characters hard, but at the same time, that's what I feel for all characters haha.

But, I feel I can understand their motivations as characters. And understanding that as well as having a general sense of how they act as people makes it easier for me to get into their characters.

I'm definitely rambling lol, but, to clarify my "it depends" answer, oftentimes it's the person whose POV I'm not writing who's harder to write because while I know what they may be thinking, the readers don't, and it's harder to imply those things when people in general don't say what they mean and are always unreliable narrators. It's harder to write Alhaitham with any sort of emotion because it's so subtle a lot of the time. It's harder to feel I've written Kaveh well because he has so much happening with his character. They've both got their ups and downs so it really depends on the situation they're currently in. 💜