OK. Another can of potential worms.
Harley Quinn's origin within this film.
So far it points towards the new 52 origin that has a few more backstory points, as opposed to the more basic and slightly more elegant Mad Love origin (52 version still has much of the mad love elements). And I think people are getting quite amped and annoyed by that - but having just reminded myself of both origins, I'd love to see it play out like this, matching up to what we know from the trailers so far...
Harleen Quinzel is a psychologist most likely studying the criminal mind (and has a dark fascination with it) and has a job at Arkham where she ends up meeting the Joker, probably intentionally. I think she organises sessions with him restrained, but as they go on, he slowly convinces her to undo his restraints (I think we may only be shown this scene rather than the prior meetings, but they will be hinted at) and of course he could easily kill her, but doesn't. Probably allows himself to be restrained again after threatening her. This rush of adrenaline and what could have happened but didnt puts her on a dark path where the culmination is his release or escape. As they are on the run together, she sees a darker side of him (the much photo'd car/gun/her in normal clothes/him in a suit) and rebels at his "control" a bit - and is slapped by Joker etc to ensure she knows who's boss. He takes her to where he himself feels like he was "created" - but he doesn't push her in.
At this point I think even I (who is a massive proponent of taking the story as it is, not how we want it) think she shouldn't be pushed, BUT she probably will be pushed. There are elements of interest in being pushed - Joker's isolation, he wants someone to be like him, he wants to control her, he needs an ally, he is just having fun "unlocking" her and this is one of the keys etc- but I am not certain whether she should:
1) Jump in herself
2) Accidentally fall
I think jumping in herself would have awesome dramatic weight. it shows she is unhinged enough and devoted to him so much that she is willing to emulate him, and it represents a perfect opposite (if he fell into there) for the joker to contend with. We also have the fact that there are blue and red swirls in the chemicals, which could mean that she has already dyed her hair prior as per New 52 origin - but she doesnt have the hair dye in the car/gun/slap scene. So perhaps he dyes it for her between /whilst torturing her (or the torture allows him to control her) before pushing her into the chemicals.
Accidentally falling would be lame I think, but could lead to an interesting moment of the Joker trying to save her just by reaching forward - allowing us to see he does have emotions towards her. Which would be powerful before he jumps in to collect her.
I think I'd really enjoy her jumping in herself. Possibly with the Joker making a little "Oh...she went there. Nice." face before he jumps in after her as we have seen.
TL: DR Harley's origin within the movie, should she be pushed into the chemicals or jump herself? Thoughts?