Possession: Give [character] a power action and make a close combat or a ranged combat attack (as if he has a range value of 4) against an opposing target character as a free action. A successful attack deals no damage. Instead, remove [character] from the battlefield and put him on his character card; the target is possessed, becomes friendly to your force and opposing to its owner’s force, and any of the target’s canceled powers return.

After the resolution of any action given to the target, you can release the target. Remove all action tokens from the target and place [character] in any unoccupied square within 4 squares to which the target has a clear line of fire. The target becomes friendly to its owner’s force and opposing to your force.
If the target is possessed at the end of your turn, roll a d6 and add 1 to the result for each 100 points (or fraction thereof) of the target’s point value. If the result is 6 or more, the target is released. If the result is 5 or less, deal [character] 1 unavoidable damage.

Each time the possessed target takes damage, deal [character] 1 unavoidable damage after the action is resolved. Any effect that can counter the target’s powers can counter [character]’s Possession. If [character] is defeated or Possession is countered or canceled, the target is immediately released. [character] and possessed characters can’t be targeted by Mind Control or Possession.

If I use Possession on a character, can I use that character's feats?
No. Only the player that paid the cost to use a feat in its build total can use a feat. Possession and Mind Control do not allow you to use feats you did not pay for.

What happens if my character must stop using Possession, but there is no square available to which it can draw line of fire as described in the Possession description?
If you must stop using Possession, simply place the character in the closes available square. If you are trying to choose to end Possession, you can't choose to do so until you can draw line of fire as described.

My Hulk (or whomever) has Battle Fury and can't be Mind Controlled. Can they still be Possessed?
Yes. Possession is not Mind Control. Any game effect that specifically mentions one, and not the other, has no effect on the other. For example, the Violet Lantern special object (which deals with Mind Control) has no effect on Possession.

My opponent has only one character left on the map and I Possess it... what happens?
Once the Possession action resolves, your opponent has no more friendly characters on the map. The game ends. Note that this is different from Mind Control, where the Mind Control action can't resolve until the controlled character is given a free action and thus reverts back to its original owner's control.

However, since you did not defeat the Possessed character, you do not score any victory points for Possessing it in this way.