It's that the characters almost always react a certain way.

I was thinking more about this and realizing that my attitude about that - that I wish I could vary my characterization more - only applies to fanfic. In original fic, like if you're writing a series, it's universally considered right and proper to solidify (expand and deepen, sure, but along in-character lines) your character as you go and not dart off into sudden OOC areas. But for some reason, I would at least like to go beyond my comfort zone with my fanfic characters, you know, and do something quite different. I don't know why I feel like that.