My favourite to write is my A.J./Tesia series because Tesia keeps growing up, & still loves her brother no matter what he's done or what she's been through. And A.J. is trying to be bother her brother, and a father-figure to her. Plus he struggles with having her in his life so frequent in the later fics, because he's so used to being free to do what he wants without having to worry about who is going to look after her while he's out. It's also got depth, with the abuse Tesia suffers, & all the emotions & everything.
As for the hardest thing I ever wrote - prolly, anytime Brian dies in a fic. It happens very rarely, but when it does, I feel like my heart's being ripped out for doing it. I just admire the man so much. Love him too! Lol.
~Lenni~