Nothing lands a roleplayer in hot water faster than when they write another character’s actions incorrectly. And by actions I include, personality and emotions. Especially personality and emotions.
As roleplayers we have a responsability to write other characters as their owners intended. You might have a strict no-godmodding rule in your game, but there’ll be a time where you might have to at least mention another character’s actions, and you’d better be damned sure you’re playing them right! Because I’ve seen people launch into full flame wars and quit because their characters were written incorrectly.
By “written incorrectly” I mean that someone has put words in a character’s mouth that they wouldn’t say, or made them do, think or feel something that they wouldn’t.
Some games allow godmodding
Actually I think this is quite progressive, because I don’t think godmodding is all that bad (I wrote an article about that here), as long as everyone in the game trusts each other and really understands each other’s characters.
Writing for other people’s characters can push the game’s plot much faster.
But you can’t assume another player’s thoughts or feelings
The typical “Mary Sue” trope is a happy girl whom is smart beyond her years, and is liked by everyone (more about the origins of the Mary Sue here).
But “liked by everyone” means you’re controlling other characters emotions? I’d draw the line here because this is godmodding at its worst. How do you really know what another character feels towards yours, without them at least meeting, having a conversation, and also yourself having a conversation with the other character’s player.
Of course Mary Sue does mean so much more, and we’ve got a list of all the types here.
Don’t assume anything
Check with the other character’s player first (I suppose some people call this a “mun” but I digress). They might be happy for their character to be friends with yours. Or they might think they’d hate each other. But either way, a relationship (friend or hatred) should probably be roleplayed, wouldn’t that make an interesting story? The bromance of how they became friends? Or the tale of how they came to hate each other?
Every character is different
Some characters are friends, some enemies, some have more complicated relationships. Don’t just assume all characters will like yours immediately.
Top image is by Meb90 on DeviantArt.