I'll never forget one of my first campaigns, where a few sessions in, the one "edgy" character in our crew of demented murderhobos decided that he didn't want to go in a cave that the rest of the party were going in. Nothing could move him on this.
Every 15 minutes or so through a multi-hour session while the rest of us explored the cave and fought beasties, the DM would ask him what he wanted to do, as a kindness that turned into a running joke by the end. His character was determined to use his abysmal crafting skills to try and make caltrops from stones outside the cave. I think that when the average rolls were calculated out over the time it took, he crafted something like three poor quality caltrops.
The player insisted that he was fine with all of it, seemed to have fun just hanging out, and it did technically fit his character. Still, it really cemented the importance of being flexible with your RP to not kill game flow.
A session or two later the DM gave each of us a "joke" magic item of questionable utility. Edgy got a pouch of infinite stone caltrops. The DM then learned a hard lesson about the cheese potential of "joke" magic items.
Full credit to the guy for managing to play 40 sessions like that, though.
Characters rarely, if ever, turn out exactly as they're envisioned- that's part of the beauty of them. As long as you play someone that works well with the team and keeps the party together so everyone can enjoy the adventure, then you've done well. Sure, this guy probably turned out to just feel like a haunted, cold person travelling with the party for no clear reason, but that can still contribute to having a solid party dynamic.
I'm playing a Star Wars Saga Edition game right now where my character is a former privateer fighting in the Jedi Civil War for the Sith. He was fairly honest with his party members about his former criminal affiliations, that's how he met them in the first place. The fact he was on the wrong side of the war only came out when a conversation about the war came up and he was directly asked about it. The Jedi in the party took it surprisingly well, but that's probably more due to the conversation being completely unserious other than his admission.
Lesson learned: you can probably trust your party with your dark past.
I've always wanted to make a rogue with a super edgy back story and they are wearing black and all that with a mask but as soon as you talk to him he is just super enthusiastic about helping people and is super friendly with an NZ accent.
I'm in a campaign (with rotating GMs) where I'm playing a character who is literally an alien infiltrator that has infiltrated the party. Except he's really bad at it and it's obvious he's an alien infiltrator, and because he's bad at it he has no idea that it's obvious. The party's superiors told them to play along for now and try to find out what my character is up to.
It's been about four years now, going on five, and I practically had to spoon-feed them useful tidbits about his mission. I've finally just kidnapped them all and took them back to my homeworld, we're now running through the adventure where they escape. I had to put an alien diplomat in their cell to monologue information about them.
Still, I've been having fun so I don't mind. Just amusing how much PCs are willing to trust other PCs simply because they're PCs. :)
Sometimes it's different for NPCs, but not always - in another campaign just now the party encountered an Aboleth who told them that he was a good Aboleth that wasn't interested in mind control or manipulating anyone. And by the way, there's this list of quests he's working on and he'd appreciate some help. They jumped right in. He actually is on the level, but come on - Aboleth. If there's anyone to be instantly suspicious of it's someone like that.
Had this happen in a Savage Worlds campaign set in the old west. My gunslinger Mark Reid was only 5’ 6”, slight of build, and appearance half hidden by their slightly oversized debt hat and tinted glasses.
They were actually Maryrose Caroline O’Shannon, from a semi-wealthy Irish family. She’d ran away to US to avoid an arranged marriage.
I’d dropped a few vague hints, but we were playing online, so they were easy to miss. I thing the GM was planning on her old life catching up with her at some point but the group broke up before anything was ever revealed.
(Mary/Mark Read was a real life female pirate who posed a man until she ran into Anne Bonnie & Calico Jack Rackam. The character was kind of a combination of Mary & Anne, visually leaning towards the pretty boy appearance of Leo from Quick & the Dead.)