'Suicide Squad' director David Ayer has hired a ''therapist'' to stop his cast going too far in their roles.

The filmmaker is keen for his actors, which include Adam Beach as Slipnot, Jared Leto as The Joker, Will Smith as Deadshot and Margot Robbie as Harley Quinn, to be ''tormented'' during shooting of the movie, but he doesn't want them getting too ''villainous''.

Adam told E!: ''David Ayer is about realism. So if your character is tormented, he wants you to torment yourself. He wants the real thing.

''We kind of have like a therapist on board if you fall off the wagon and really are villainous.

''There's a friend of [Ayer's] that's very unique in making sure we have our ground.''

Explaining the filmmaker has hired a ''life coach'' rather than a psychotherapist, Adam admitted the director is concerned his cast will ''disappear'' into the ''dark side''.

He added: ''Us actors explore very fine thin lines going to the dark side and he wants to make sure we finish a movie and don't disappear somewhere and then don't show up for work.''

It was recently revealed Jared has sent a live rat to Margot, bullets to Will and a dead hog to the rest of the cast as part of his own preparations, and also sent a letter and video explaining why he hadn't joined his co-stars as they took time to get into their characters.

Adam said: ''Basically, what he said was, 'Guys, I can't be there but I want you to know I'm doing my work as hard as you guys.

''The video he showed is in character. It blew our minds away. Then we realised that day, this is real.''