[OOC]

Backtagging: Absolutely!
Threadhopping: Generally fine, as long as it doesn't get obnoxious :'D
Fourthwalling: Prefer that he not be fourth-walled. As for the reverse -

• no comic-book canon from our world exists in his. They do have comics, just different ones.
  
• literary and movie canons are more likely to exist (e.g. Ayn Rand, the Twilight Zone, & Silence of the Lambs are explicitly mentioned in-series), but I generally won't assume they do without asking.
  
• Qubit is probably woefully behind on pop culture anyway. He's more likely to be acquainted with tropes than with individual franchises.

Subjects to avoid: Prefer not to mess with graphic sexual content.

[IC]

Hugging this character: Go for it. He'll react differently depending on who's doing it, of course, but with friends he's generally fine with it.
Kissing this character: You can try? I mean, skin-to-skin contact is physically painful for him, so it may not go over well, buuut it's not like he goes around telling people about that issue.
Flirting with this character: Sure, though it might take him a bit to catch on.
Fighting with this character: Absolutely! Qubit gets in fights all the time, he can handle himself (usually). Either way, he routinely provokes people who can punch him through walls, so chances are good he had it coming.
Injuring this character (include limits and severity): Cuts and bruises are fine, he's no more durable than a regular human. Talk to me first for anything that'd put him in the hospital.
Killing this character: Talk to me, but I'm open to the idea.
Using telepathy/mind reading abilities on this character: Depends on the situation. He's fine with telepathy for communication purposes, but his psionic shielding is specifically designed to prevent unauthorized access, so you won't get anything out of his mind without his express permission.

[NOTES]

Qubit can be a manipulative sack of shit at times, specifically when dealing with someone uncooperative whose cooperation he needs. He avoids outright lying, but will freely use half-truths, lies of omission, and outright threats to get the behavior he wants. It's all in the name of good, of course, but uh... I guess what I'm saying is I take no offense if your character punches his face for this. Even Qubit kinda knows he deserves it.

Also he tends to double-cross bad guys on the occasions he has to work with them, so uh. keep that in mind if you are a bad guy.