Jessica Jones has proven itself to be not just one of the best television adaptations of a comic book/graphic novel but also one of the best works of television in recent years.
It's also "broken" the barriers for the superhero genre. Jessica Jones is a Marvel (and superhero) first for rape,abortion,PTSD and drug and alcohol abuse. Kilgrave, played by David Tennant has also proven himself to be one of the best live action comic book villains to date. The show can also be considered the first "X rated" Marvel production.
Now, I'm fully aware that Sucide Squad isn't a Marvel film/comic but if this film isn't going to be rated R (it's been confirmed to be PG-13 I believe) I want it to use some of the aspects that made Jessica Jones great without going too violent/dark (let's just call that "R" rated territory.)
With that being said I want The Joker and the films other villains (which is basically all the characters but for the sake of this lets just focus on The Joker) to be just as dark and minupaltive as Kilgrave.
Kilgrave is a character who you seem to want to empathize for and still like even though he's a rapist and a murderer. Even without his abilities Kilgrave was still able to minipulate and mess with Jessica. If you also remember when Jessica had him locked up at that abandoned facility he tried to get people to let him out by crying or even writing "help me" with ketchup. I want and hope that The Joker can and will make you feel the same way. Judging by Leto's previous work he should have potential to do this with the character.