In our stupid roleplay that nobody actually cares to apply rules for (thankfully), I noticed my Asuka said I did a few things when I hadn't agreed to having done them, or said them, or what have you. We later confirmed she genuinely didn't know this was in bad roleplay etiquette, so in case anybody else is in the dark to this aspect of roleplaying (though being intermediate or advanced means you probably already know, but
just in case 
), here's something I found on another forum.
I didn't have explicit permission to repost this... So all credit goes to
this post. I just thought they were good examples is all

The part about Jim's player seeing another thread is more of a RHHS-specific thing. They have this huge forum for one RPG ~_~ It doesn't apply the same way here, but if a character didn't tell you directly anything about their past, even if it's in their character profile, your character can't have known it (even if they're a mind reader - there's nothing to say character 1 was thinking about their past at the time you decide to mind read. If they were and it said so specifically in the post char1 made previous, then sure I guess xD). Keep that in mind when reading your RPGs

EDIT: God-modding NPCs is fine. It's up to the GM as to whether they're allowed in a certain RPG though! If they aren't that information should
probably go in the sister thread.
Example is family. They're allowed to be part of a character's history, and you can talk to them on the phone and stuff. Usually player-on-player RPGs prefer to have as little major NPCs as possible and much more player-on-player interaction, so NPCs usually don't twist the story, just to make it more interactive and interesting for all parties.