That's kinda why I had to leave my group last week (still reeling from that, we had some amazing times. Many more than I even shared here). Fricken OOC in IC. This player's personal charisma and long winded speeches kept winning in-game concessions for his 12CHA barbarian (no points in social skills). He bossed the party around too, according to a bizarre set of behaviors I didn't understand OOC much less IC. It finally came to a head when I tried to introduce yet *another* new character, and...
Okay so my character is a volunteer guard in the last bastion of good on the planet, a camp of elves druids and fey around an enchanted wizard tower. I'm actually neutral, because the barbarian character is evil as hell. He denies it in and out of character, but he's half-possessed by a devil worshiper and has to eat a sentient creature every day to survive. He does nothing to remove either curse. He's evil evil evil argh it feels so good to be able to say it, because mentioning it at the table always sparked so much bullshit outrage. "Beyond morality" my ass.
So yeah there's no way I can join them as a good character, so I went with neutral again. A hardened veteran from the waves of rogue necromancers who periodically try to overwhelm the tower's sanctuary. I patrol the energy barrier (which weakens undead), leaving the corpses outside the edge. Then I see the party. They're chasing a young boy on the edge of town.
"Stop! What is your business here?" I ask.
"What is *your* business here?"
"I protect the sanctuary from necromancers. Are you necromancers?" They are being followed by an NPC who totally is a necromancer.
"Maybe *you're* a necromancer!" The wizard readies an action to cast a spell
"But... I just killed all those other necromancers. I clearly live here."
"Whatever, we're going inside"
"I can't let you do that until you explain your business!" I draw my ceremonial shortsword, mercy enchanted.
I die to finger of death.
We decide that I clearly cast Death Ward on myself before each patrol. I'm a shugenja, I certainly have enough castings.
"You just tried to kill me!"
"You started it, you drew your sword!"
Some bickering later, I manage to learn that they want to defeat the cultists who have occupied Highcrest, the last major city with living people. Formerly a bastion of paladins, but we sure screwed that up... They need someone who's good of heart to hold an artifact, hence their attempt to recruit a child.
"The devil worshipers? I hate them passionately. We got off on the wrong foot, I'll help you find someone."
"Cool. Also we're responsible for the recent disappearance of an entire continent, which caused massive worldwide flooding." I don't even remember how this came up. It sets off alarm bells for my character since he was basically granted his powers to restore the wounded planet. Instead of killing them, I decide I need to follow them to find out what happened and how to fix it. Maybe it was an accident. IDK, I was trying hard to justify joining the party.
"That's... interesting... I'm going to need to accompany you. I believe you're going to fight the cultists, but I can't just let a kid from the camp leave with some strangers."
"You don't trust us!? But you attacked us for no reason!"
"I - what? I drew my sword! You were about to walk by-"
"Hey wear this collar, it... protects from mind control" The collar allows you to be voluntarily dominated. It does protect against mind control, through mind control. Later the barbarian's player swore he wasn't lying, even through omission. Such BS.
"Wow, no. I find that highly suspect. You just cast finger of death on me. I'll just accompany you-"
"You're acting super suspicious we're going to ignore you now!"
I follow them into the settlement. There are several unicorns and pixies around, casting detect evil. A pixie runs up and accuses them of being evil. Another chance for me to earn their trust!
"Don't worry, they're with me." To the party: "Don't worry, I kinda suspected you were evil. But I don't care, as long as you're working against the devil worshipers-"
"I'm not evil! That pixie's racist!" This would be interesting IC except that the player rants about this OOC a lot. He actually believes the character isn't evil, in-universe concepts of morality be damned.
"Er, sure. Okay. Ha, yeah they are kinda annoying."
Suddenly the DM has the favored soul of Pelor, a twelve year old kid we've met before, arrive and try to join us. I think he and I both wanted to move things along. This is perfect!
"Hey Jason, where's your mother?" - the evil half-ogre barbarian
"I dunno, can I come with you please?"
"No, we need to ask her permission first. Family is important" - the barbarian who just yesterday bought a human slave from ghouls and ate him.
I speak up. "Uh, I don't know if his mother will go for that. But she doesn't have to know. He wants to come along, and I'll be there to keep an eye on him-"
"Whaaaat? You want to *abduct* this kid? Are you a necromancer!? You're definitely not following us." the barbarian's player is openly mocking me. It's pretty funny, which is why people are laughing, it's just also really shitty. I start to lose my cool.
"Psst, look - Jason only wants to follow you because I'm hiding the fact that you attacked me. I don't trust you, and you're not taking him without me!"
"GUARDS, THIS IMPOSTER WANTS TO ABDUCT THIS CHILD"
fuck it. That's when things devolved to shouting, followed by sad apologies. But this shit was just so typical, reliable even. I just couldn't stay. I was metagaming to get the group together, he was making a joke of me and my character. And as usual, justifying it as "You don't understand my character, stop policing my roleplay!!" He stood by all that stupid stuff his character said, claiming he had every reason to be suspicious. Based on all those sense motive rolls - OH WAIT we only rolled one at the start, and it confirmed I was a concerned guard. But screw that, clearly his character would still suspect mine because he felt like it. His bullheaded "roleplay" cares not for game mechanics, IC knowledge, or other players.
I feel like the only proper IC response would have been to say "You're insane!" and stop them. Which... You just can't DO that in a party based game. Not when you're using so many splatbooks, building a decent character takes like 4 hours minimum.