[ O O C ] Backtagging: Yes; my job keeps me busy a lot, so this is very much okay!
Threadhopping: Yes!
Fourthwalling: Yes, especially for characters that would be familiar with canon Adachi.
Offensive subjects: Adachi's not big on children getting involved in anything like he has to deal with it; it's a big stumbling block for him in his story, especially since the majority of his team consists of teenagers. Generally, Adachi's a cop, so there isn't a conversation that's going to make him uncomfortable enough to stop.
Same for me; I'm fairly open about everything. If you're not sure, feel free to ask.
[ I C ] Hugging this character: Herodachi's love hugs, and generally blush and turn into little tsundere messes.
Kissing this character: Same as above.
Flirting with this character: Chances are, he started it.
Fighting with this character: Adachi generally tries to avoid fights with people he would generally consider potential allies. Considering he has a force of Personae behind him and he knows how to use them, it's generally a bad idea to challenge him. He's not that much of a slouch with a sword or a gun either.
Injuring this character: Yes, that's fine! In his story he's already dealt with a broken arm and a bullet in his leg; he's a tough little guy.
Killing this character: It would need to be discussed first, but I'm not completely closed to the possibility.
Using telepathy/mind reading abilities on this character: Yes, that's fine; keep in mind the number of Personae he has as part of his unconscious that might get in the way.
Abilities/Warnings: "Herodachi" is a role swap, so he has the powers of the P4 protagonist, meaning he's a Wild Card, can form Social Links with others, and has a number of
Personae at his disposal. In game, he only have access to the Personae that match up with the Social Links he's made.