Permissions
Threadjacking: Totally allowed. Yusuke just needs it sometimes.
Hugging (and/or shallow affection): It's allowed, but not all too encouraged. It's Yusuke for crying out loud. He's still a delinquent.
Kissing (and/or intimate affection): Allowed, maybe. Sorta. Same reason as above. It would be better if you ask or talk to me prior for this boy's sake.
Relationships: Is a no go. I can't just have him going after anyone else except for Keiko (whether or not she joins.)
Punching/Hurting (provided he can fight back): Absolutely. Sometimes abuse is just necessary for him. He will hit back, twice as hard if possible.
Injuring: Of course, just be sure to plot with me ahead of time.
Killing: I'm an angst whore, so yes. Similar to above, I prefer to plot it out ahead of time.
Brainwash/Mind control/Etc: Again, absolutely. This may take serious plotting, but I'm all for causing havoc where it's not needed. 8Db
Fair Game Knowledge: Regarding Yusuke and his friends. Especially Kuwabara.
Threaten/Hurt/Injure: Expect to win a spot on Yusuke's bad side. He's rather over protective of his friends. He will not hesitate to attack back, though he likely wont kill if it's not very serious. This only amplifies if it's Kuwabara.
Maim/Fatally wound: If you have a death wish, this is a good way to do it. (If it involves Kuawabara, that just makes it worse.)
Torture/Control/Possess: It's likely Yusuke wont ever forgive you and will probably try and hurt or kill you depending on the situation.
Kill: You'll forever be Yusuke's enemy with no signs of forgiveness. If you kill his friends, he will kill you. (Again. Amplifies for Kuwabara.)