Ever had a character in your head that you thought was really interesting, only to end up writing them out and finding they were horrible/not what you expected? I remember way back when I first starting writing at the age of 13, I had a character who was supposed to be this cool, calm, and all around cool guy as a side character. He was supposed to be the guy my MC admired and looked up to. But after actually putting him in the story, he just ended up coming off as cold and uncaring with no personality. I also had another story where in my head, the MC was a somewhat confident girl who could get by on her own, but she ended up being sorta whiny and bratty (To be fair, she was thrown into a situation she didn't want to be in right at the beginning of the book) How about you guys? Any characters that took a 180 once you began writing them?
(Side note: this might have been better placed in the Character Development section) A complete 180? No, can't say that I have. But my second attempt at writing a novel was a story about a young priest in a terribly impoverished area, in which one of the other characters was an abrasive social worker who took an immediate dislike to him. My plan had been to keep them at odds with each other as they each tried to help the people in the community, always maintaining tension between them. As I developed the story, their personalities made it impossible for them not to become warmer toward each other, and at one point she (the social worker) actually found herself attracted to the priest. I eventually completed a first draft of the novel, but set it aside as untenable for other reasons. I would hazard a guess that you might have had the experience you did because you were 13 when you wrote it. Developoing characters, especially "side" characters, takes more work than may meet the eye. If you were to try the same exercise now, you'd likely have better success at meeting your original expectation.
I was recently reading a very old draft of something I'm reworking now, and some of the differences in characters were hilarious. My main guy was a complete raging asshole - I'd meant for him to be slightly roguish at most. A character who ended up being villainous was, in this older version, kind of just pathetic and everyone constantly shut him down (I was talking about the whole experience to a friend and joked that he'd just gotten sick of how he was treated in the draft and that's why he's a villain now). A character who was supposed to be intimidating just came off as sad and ridiculous. Granted, this is a difference of about ... well, almost ten years, actually. A lot of it was just that I wasn't a particularly good writer at the time. But even across short periods of time, my characters do tend to change the longer I spend with them, and deviate from what I originally intended. It's usually for the best. I invest a lot of time into development, though, so by the time I start actually writing I usually know them quite well. The main guy from the draft kind of is a raging asshole, in that he has some pretty severe anger management issues, and it makes him more interesting than the bland watered-down Han Solo expy he started life as.
My characters for all intents and purposes are good, but they do some pretty evil shit. From slicing up enemies leaving them disemboweled, limbless and headless, fragged, broken necks and a broken spine, jamming the muzzle of a rifle into an eye socket to muffle the shot, torture for fun and information, using a surgical retractor to dangle a guy by his cheek like a fish on a hook, pistol whipping to break the orbital socket, beating a guy until he has no face, smashing a dude with a heavy warhammer sending his insides oozing from between the plates of his body armor, crushing a guys head, and the funniest though it didn't work but to be fair the MC was kinda out of it due to shock of injuries, but they made a Merc sit on a live grenade. And they are suppose to be the good guys. Though they do a fair amount of quick and dirty emergency medical procedures that save the injured person life. Though I do not think getting a red hot pen in a bullet would would be all that nice, but it stopped the bleeding in short order. Also having a bullet removed without anesthetic while having a conversation. Just cause they are good, doesn't mean that they can't be bad. (Get your mind out of the gutter you pervs.)
He didn't turn out rubbish, but yes, I've got a character in my current work in progress who turned out differently than I planned. Joel was originally meant to be a good guy. The female main character was supposed to have a choice between Joel and another guy, but there ended up being a lot of chemistry between her and the other guy, and none at all between her and Joel. Joel then developed into an antagonist. It's not a complete 180, and he does try to do the right thing in the end, but for most of the story, he's pretty close to being the opposite of what I originally intended him to be.
My female MC as originally conceived was this sweet innocent thing who had to fight to make it in a mans world (yuck - what was i thinking) , she was also physically at least based on one of my best female friends. By rewrite 4 she's now an ex prostitute hiding under a stolen identity who gets blown up (though not badly hurt) while giving a guy head in the first scene. I am going to have a shit load of explaining to do to my friend Caroline if/when this book see's the light of day. In the same story I've got a guy who started out as your hometown action hero type, but he was so wholesomely good that I couldn't stand it, and he morphed into a guy who masks being a colossal pervert and deviant under his facade of wholesome goodness and who eventually gets stabbed in the groin by the male MC and left for the scavenging wildlife to eat alive
I had one guy who was so crappy innocent and blue-eyed I couldn't stand it. He morphed into this equivalent of the early Claus von Stauffenberg, and no, he is not innocent anymore