WRITERS: Have you ever envisioned a character of yours one way, but after a few pages....?

Yes. When I started writing a passage about the Captain of a group called the Dark Riders, he was initially a brutal, evil man. Several paragraphs later, suddenly he's in cohorts with the prisoner his men have taken. It seems that my characters want to be a certain way and just end up like that--sudden inspiration turns them from dark and evil to good and... well, still pretty dark.