I discovered long ago I'll read anything if Neville's in it, even if it usually contains kinks or characters that would squick me away otherwise (Hagrid/Neville, anyone?). The fact that you have Neville knowing it's wrong and feeling guilty about it helps a lot.
I just never thought I'd write chan myself...or bestiality, for that matter...Next thing you know I'll be writing Longbottomcest or something! o_O