5 The Joker Spoilers From Batman V Superman & Suicide Squad Trailers

Moving on to Suicide Squad, and there's a brief scene in the trailer which features a shocking reveal about the origin story of Harley Quinn. In the comics, Harleen Quinzel is an Arkham Asylum psychiatrist who falls for The Joker after she begins treating him, and subsequently transforms herself into Harley Quinn to please him. 

Disturbingly, this preview points to The Joker being responsible for her transformation. After attacking a location which looks an awful lot like Arkham Asylum, he can be seen tormenting a clearly terrified Harleen, which from set design looks to be the same scene as his character reveal at the end/

Piecing the clues together, it seems like the villain is going to use electroconvulsive therapy to scramble her brain and transform her into his sidekick. In fact, he probably brands her with those tattoos as well, making their relationship more horrifying in Suicide Squad than it ever has been in the comics. It also makes Harley a more tragic and sympathetic character, especially as she didn't choose to be this way. 

Set photos have shown interactions between the two with Margot Robbie as Harleen though, so perhaps she chooses to let The Joker turn her into Harley, with the only way he can do that being to wipe out what she used to be. Either way, it's still extremely messed up...