Character: "X" / Phantom Thief Sai
Backdating: Absolutely! I'm... e-extremely likely to do this too, so never feel bad about it.
Threadhopping/jacking: So much yes. As long as the conversation isn't marked as locked or private (in which case, just ask!), I don't even mind if it's seriously contributing to the conversation or just plain ridiculous trolling. I promote trolling, in fact! I come from DDD, man, we live off hilariously stupid threadjacking.
Intimacy (being hugged, kissed, etc.): It all depends on how he feels and who the person is. On a good day, you'll get away with touches and hugs; other days, he'll flip his shit and throw you as far as he can. When it comes to kisses, he won't really understand the intent behind them, so once again, you might get a blank look or a punch in the face.
Violence (being slapped, kicked, etc.): He does not like to be hit, especially now that he has all the physical strength of a very scrawny, frail boy. While previously he might have laughed it off, now he'll probably lash out at you - so if you want to be violent with him, just be ready for possible murderous rage in return.
Things this character is capable of/can do to yours: Route has taken... pretty much everything that made Sai outstanding. He can and will attack you, but he'd be easily overpowered. He's going to be trying to teach Ditto to make Red Boxes, but until that point, he can't do anything much.
For reference when his abilities haven't been stripped from him, Sai has the ability to transmogrify into anything living. He can match a person perfectly, and he's also discovered that he can mimic animals perfectly too - except that the impression you get from him will still be something chilling and murderous, no matter what form he takes on. He can also transform into a strange shapeless form, at which point he will envelop a person and cut, grind and crush them; their entire body will be compacted into a nice little square of a minced-up corpse, which he will then usually put into a glass box.
Anything else: Sai is almost perfectly androgynous. He wouldn't normally bother with having a gender because it's not necessary, but Route has forced him into a normal body, and it chose his default form, which is male. So, if you see him naked, he's a guy - until that point, his voice is a perfect balance of feminine and masculine, and his figure and features make it that he could easily be mistaken for a girl, or pinned down as a boy. (As a bit of a The More You Know? Sai is actually a girl, but he doesn't know at this point; his true form, his original self, is a young brunette girl.)
Anyone who tries to read his mind will be assaulted by the disjointed and insane thoughts of someone who is very, very cracked and has an absolutely crippling case of identity crisis.