When I was in college I had my first chance to play some TRPG. I played half-a-dozen one shot there but then I dropped out and when I enrolled again I couldn't find another group. Now, years after that I've finished college but wanted to try building a table to start playing again.
However, the last session I played left me with quite a bitter taste in my mouth because of the following story:
We were four or five noob players (started playing together in college) and only our GM had some kind of experience. It was a medieval campaign and my character was an arrogant knight who followed the king (NPC) everywhere, basically being his dragon.
The story was about a secret revolution that would overthrow the king, and the party consisted of people of various backgrounds that would unite and plan the revolution. Everybody was neutral, but mainly common people who were oppressed.
I was not only loyal to the king but an asshole who kind of embodied what the people hated about the kingdom. My character arc (I only imagined it, never told anyone) was to somehow have a change of heart and sacrifice myself to defeat the king, betraying him.
Most PCs didn't have the chance to interact with my character, as they were moving the revolution sticks with its leader (NPC), except one. He was a hermit swordsman who encountered the king and tried to talk with him respectfully. Being the brute asshole sidekick I intervened and treated him very badly, putting him down and saying he was a commoner, should respect the king, all that jazz.
I think that was very much in character and I didn't swear or make any OOC insult, but the guy playing the swordsman tried to start a fight with my character. I avoided (deriding his character for being too weak) and the GM played along, as we noticed it was too early to fight and since we both were LVL 1 there was a chance he could win and completely demoralize the big bad.
We went on playing and at some point, my character was on a mission to kill some elves in a forest. The mission was successful but the swordsman appeared there and we fought. I had the worst of luck with the dice and he ended up owning my character, which was left unconscious. Now, it would be the perfect time for him to humiliate the character in some way or move the story forward somehow but the swordsman was also a werewolf.
He asked the GM if it was a full-moon night and the GM rolled the dice: it was. So, he transformed into a werewolf and his character "lost all senses". The next 10 minutes or so, he described in detail how the werewolf tied my character to trees, dismembered all his limbs one by one, and used some of his skills to bandage all up so my character wouldn't die.
I could do nothing but watch since my character was unconscious, the other characters were absent, and the GM didn't want to force anything in. So, after he finished "roleplaying" he said, IC, "Serves you right", with a smirk.
Afterward, everybody seemed uncomfortable including me. But, since I was a noob I just figured those kinds of things happened in RPGs and rolled with it. I began imagining ways my character could still be useful as a human stump but since he was a knight, all his attributes were physical, and without a body, the character became basically useless.
The GM noticed this wouldn't work out and right before the end of the session he used a deus ex machina to revive all dead elves and restore my body with some ancient forest magic that had been dormant. I never played again with that group since I dropped out of college a month after for personal reasons.
I just want another perspective on this before I start playing again. Did I deserve that? I mean, the character was an asshole so he deserved what the swordsman did to him. However, it was also completely unnecessary and I felt like the other guy wanted to punish me for my roleplaying.
He claimed later that since I was being an asshole IC he also was cruel IC. But I felt his actions had the intention of hurting me as a player since I couldn't play anymore after having a crippled character.
EDIT: Thanks for all the answers! I agree this is kind of and open-ended question so I will not choose a "correct" answer. I believe all the perspectives and resources linked helped me in understanding how to better play from now on.
Just to clarify, what bothered me the most wasn't being killed or even tortured (although I think it was unnecessary) but the clear effort to let my character still live after all. We were playing with a system that allowed us to create a new character using the stats from the dead one, so I wouldn't mind dying and creating another one. But to me it felt like he tried to make me useless OOC unless my character commited suicide or something like that.
That being said, now I agree that choosing to be an antagonist, even if you wish to change that along the story, is a very bad idea, especially with unexperienced players like us. My character had some interactions with other PCs as well and they all behaved quite normally (they were afraid in his presence but bad-mouthed him when he left), but still.
About our GM, I felt he tried to give us as much freedom as possible, since we were all new to this and maybe he thought too much rule-lawyering would scare us away. In a previous session (with another group but same GM) I also chose to be the literal bad guy, and we enjoyed playing the parallel sides, until in the end the party defeated me in a grisly battle. Nobody including me felt bad about the antagonism so that may have influenced me to try it again.
As for why I chose to be the bad guy in the first place, I guess it was because I found extremely boring to have something like a "four strangers meet in a tavern" premise, but I will pay a lot of attention to this kind of antagonism in my future games.
I wish this to be open for comments for a little while, but I guess the question can be closed after that. Thanks again!