While I thoroughly encourage asking people about whether or not they'd be interested in writing different plots together, I also think it'd be very useful if everyone replied in a comment to this describing who their characters are and what they may or may not be comfortable with writing with each of them.
This post was put up by the former mod, but I'm rewriting the example here since I inherited control of Lucifer. For those familiar with how she played Lucifer, basically nothing has changed. Lucifer
-- Lucifer is here for all your eviling needs. There are very few limits to the things he can and will do in the right circumstances, and he can be very cruel when he wants to be. He can also be very nice, if he thinks it will be to his benefit. But being who he is, he certainly doesn't mind doing things that people would consider bad; in fact, he often quite enjoys them. He likes making people squirm, and while he won't do anything too harmful to people on his own side (unless he's trying to punish them and make them an example), he does get a kick out of frustrating them sometimes. So, with Lucifer basically anything goes, though if it's exceptionally
violent or sexual, I may request that we not actually log it, but simply figure out what happened and continue as if the event occurred. Reno
-- Reno is pretty open as well, though unlike Lucifer, he has his own set of moral limitations. He can be very violent, but he would have to have a reason. He's not one for beating people up randomly (though he definitely enjoys a good fight.) Otherwise, he's pretty laid-back and friendly. He's a joker and outspoken at times, and if you're not paying close attention he can come off as stupid. He doesn't usually mind if that's what people think, but seeing him that way could be a horrible mistake. He's extremely observant, adept at reading people, and usually is very aware of his surroundings even if it doesn't look like he's paying attention. He can be sneaky and manipulative, he can pick locks, he can hack your characters' journals if you want him to. (If you don't want him to, it's easy enough to assume he just didn't feel like it.) I'm also willing to play smut with him, though at this point that would be highly unlikely if your character happens to not be Maria. ^_~
(I actually have a post down in the list somewhere for him, which has a few more notes about his personality and stuff, but I figured I'd write a new one as another example, and to sort of update the old one.)( More examples, but for characters played by the former Mod that no longer apply )
Regardless of what someone says, if you end up confused or just want to talk to them about a potential idea anyway, never be afraid to ask players about stuff and plot with them!