I think some intense type of prosthetics or makeup (not saying that he should wear white makeup) is needed, the various times I've tried to create a picture of the Joker he just looks too damn... nice? Not sinister enough. I think it's his eyebrows and baby faced skin.
If they can give Jared lines like Willem Dafoe,
especially when the Joker grins and laughs, I'd be happy. But saying that, I don't want him to have that Arkham look. For this appearance in SS, if he is in Arkham, I want him to look as unspectacular as possible...He's wearing a jumpsuit, and has no makeup to go along with his white skin, a bit like in TDKReturns
All he has is just his pale green hair, there's no life to him hardly. If Batman is on the verge of reitiring in BvS, then he must be confident that Joker isn't going to be around anymore. So perhaps in SS, somebody brings a comatose Joker round? That could be the case I think, but who knows?
So we see a new angle to him, he's almost like a baby being born and learning to walk and talk, becoming more and more himself as things continue...then by the end of the movie, we see him resembling his classic self and he escapes from Arkham once more.
But if he's the enemy of course, then that won't be the case.
