Permissions
Threadhopping: As long as it's not marked private and is fine with whoever I'm threading with, go for it.
Backtagging: As long as there's not a HUGE gap in time, I love backtagging. I always prefer reaching some sort of conclusion in threads.
Fourth Walling: Why not? Lithuania won't believe he's from a manga, however.
Hugging: You can. Lithuania is not one for unexpected physical touching, though, and will be stiff about it unless he's used to you. The closer he is to you the better he'll respond, naturally. Children who hug him are likely to get a hug back, however; he likes kids.
Kissing: Lithuania will push you away, most likely, but you're welcome to try. Quick kisses on the cheek will probably be tolerated, though he'll be stiff about it.
Fighting: I enjoy fight threads quite a bit, so this is always fun. He's not a pushover, and has regained his nation body, meaning his speed, strength, and stamina are greater than that of a normal human. Lithuania has hundreds of years of combat experience behind him, and when he goes into battle he gains what's been called a "battle aura", leading to improved leadership and an almost ruthless nature in the middle of a fight. He can hold his own without a weapon although he's not particularly skilled in any hand-to-hand style. He's a good, though not brilliant, shot with several kinds of guns, and is good with a dagger. If you get into a swordfight with him and you are not an accomplished swordsman, you are going to lose.
He has no real resistance to magic or other sorts of supernatural powers, and overwhelming him with physical strength or numbers is entirely possible, especially while he's human. Without a weapon he's likely to lose a fight, though he'll try to obtain some sort of weapon if he finds himself in one. He's getting into the habit of carrying a (Mayfield-bought) gun around with him.
Injury: For the most part this is fine, though if you're going to hack off a limb or rip out an eyeball or something similar that won't repair itself eventually, drop me a line first.
Death: Please contact me first; I don't mind having him killed, but I prefer good reasons for it.
Telepathy/Mind Reading: Lithuania has no particular resistance, so go for it. However, when going through his mind, keep in mind that he has 2000 years of memories in there; trying to go through all his memories may cause headaches, at the least.
Please don't mention: While I do enjoy the more serious aspects of Hetalia, I request the more sensitive aspects of Lithuanian history be left alone. If you're ever uncertain, go right ahead and ask me!
Aside from this, there's nothing in particular that I don't want mentioned. There are, of course, things that irritate Lithuania. He's proud, and does not accept or enjoy pity. Things involving Russia can quickly run right into unhappy territory, and if spoken of in terms mocking or insulting Lithuania, will definitely provoke anger. Insulting Lithuania's people is probably the fastest way to get him to dislike you. If he ever has a citizen in the game and you hurt or kill them without an extraordinarily good reason, he will hate you. Period.