FIRST AND FOREMOST, Karkat and his capslock/color thing is always opt-out. Anytime you don't want to deal with him or his writing style, just tell me and I'll be happy to oblige. All comments will be screened by default.
♋ OOC ♋
♋ Backtagging: No problem at all, believe me.
♋ Threadhopping: Generally that's fine; I make sure to mark threads private if they're not open for threadjack. If you're not sure, ask!
♋ Fourthwalling: Sure, knock that shit down and piss on the rubble.
♋ Offensive subjects: I have one major squick, and that's bad things happening to fingernails and toenails. I'd appreciate a waning at least.
♋ [IC] ♋
♋ Hugging this character: He's shelled off and crabby, so he'll probably push your character away unless the moment's right or they're someone he trusts quite a lot.
♋ Kissing this character: Sure, if you're Dave.
♋ Flirting with this character/Relationships: He's got his relationship stuff settled, but feel free to flirt if you want him to get flustered.
♋ Easiest way to get on his bad side: Look at him. Say something. Breathe. Exist.
♋ Easiest way to get on his good side: Karkat isn't a complete jackass and backs off with the attitude sometimes -- like if you've come to him for romantic advice, for instance, or just plain old advice for something else. Or if you're recognizably badass. Flattery/recognition of his leadership might work too.
♋ Can I hack his journal/phone/communicator?: If your character's good at that sort of thing, they're welcome to try and almost guaranteed a yes from me! Sollux/Psii-muns, you don't even have to ask. Hack away.
♋ Can I shapeshift/bodyswap/etc?: I'm open to these things, but let's talk it over first!
♋ Sexual orientation: Like most trolls, Karkat is genderblind.
♋ Fighting with this character: Honestly? If your character has good fighting skills, Karkat's probably going to lose. He CAN fight, and he's a tireless little bastard, but he's not exactly the best Alternia has to offer.
♋ Injuring this character: Go for it, just talk it over with me before you break something.
♋ Killing this character: Not unless it's a death is cheap kinda game, and even then let's plot first.
♋ Using telepathy/mind reading abilities on this character: ICly, he really hates that kind of thing. Respect his privacy, goddamn it. If you want to know, ask, and if he feels it's something you should know, believe me he'll tell you.
OOCly he can't do shit about it (thought in canon, at least one psychic tried and failed because his mind is terrible) so run the risk if you'd like!
♋ Warnings: Karkat is easily provoked and prone to doing incredibly stupid things in a fit of anger. Also, he's a teenager from a culture where feelings aren't spared; he uses insensitive words like "cripple" or "retard" without even thinking about it. If he's making you uncomfortable, please talk to me about it!