(Gif is from kj-svala @ dreamwidth)
OUT OF CHARACTER
Backtagging: Always ok.
Threadjacking/Threadhopping: As long as it's good with others in the thread.
Fourthwalling: Only if you are Deadpool.
ACTION
Fighting: Bring it on, though it takes a lot to goad him into a fight.
Injuries: Drop me a pm first please.
Killing: Preferably only for memes.
Telepathy/Mind-reading: Eh to an extent. Dude is a Vietnam vet, and nice as he is he really doesn't want people seeing what is in his head.
RELATIONS
Hugging: A-ok
Flirting: Also good, he will probably flirt back.
Kissing and/or other intimate actions: It happens but if it is just out of the blue with no previous inclination of interest he will be appropriately surprised.