i think that's a hard one. you can always do what they do for deadpool in the comics, which is to have his 'audience addressing script', and just do something like :so what do you think of this, faithful viewers?: or something that is specific to that character breaking the fourth wall towards an 'audience', real or not. i mean, even in dp's canon, he's known for breaking the fourth wall, but the people he's with when he talks out loud (because it's out loud sometimes) just chalk it up to him being bananapants crazy, just like in the movie. they either don't acknowledge it or they ask him who he's talking to and he says 'the viewers/audience' and they just 'okay, well, you're batshit'.

so it depends on if you'd want to play that a similar way or not. it is a bit different, since the medium itself is different (written vs show/movie), but you could always try a 'dear readers' approach, like some narrators do. i haven't played a char like that, so i'll admit, it's not something i've thought of.