The official two-player variant rules say that at the start of the game, you get two character cards, and you choose one to be your "exposed" character and one to be your "covered" character. You can only use the abilities of your exposed character, unless your covered character is specifically targeted by your opponent.
What is the point of the covered character if it's just always going to be in the background? Do the covered character and exposed character ever change during gameplay?
I haven't played this game, but the rules seem fairly clear to me.
1) You can swap which character is covered, and which is exposed, each game turn. So they don't have to stay in the background.
At the beginning of any turn, after dealing with such cards as Jail and Dynamite and before Phase 1, the active player chooses one character to be exposed and the other to stay cover. In order to do this, push the exposed character towards the center.
2) You only get to use your exposed character's ability. The exception is when your covered character is targeted, in which case you get to make a response from them instead (poking their head out of cover).
During your turn, or your opponent’s turn, you can only use the ability of your exposed character. However, if your covered character is the target of a card (BANG!, Indians!, Duel, etc...) you temporarily get the ability of your character in cover (and lose the ability of your exposed one), for the short time needed to respond (see example below).
3) Your hand size is determined by the life remaining of your exposed character.
When you declare the end of your turn, you must discard from your hand any card exceeding the current life points of your exposed character.
