Jared Leto's Joker is among the most theorized characters in DC's universe, and it seems that another one hit the rumor mill based on the actor's hat selection while away on vacation.

According to HitFix, Leto was seen wearing a hat similar to the look and feel of the Joker in Alan Moore's "The Killing Joke", which fans think is a possible link between the graphic novel and his backstory in the upcoming film.

That being said, evidence to support the fan theory has come to life, according to Geek Tyrant.

So what is the presumed story behind Leto's Joker? That he's not the original joker, but rather, Dick Grayson - AKA the Original Robin.

So how could this be explained? Everything is on the teaser, it seems.

According to HitFix, the original Robin goes insane after subjecting himself to gene therapy, and so he takes on the appearance of the Joker.

However, there is more to Zack Snyder being influenced by Frank Miller's "Batman" comics - some fans have come to the conclusion based on one small detail from two images: Jared Leto's image for "Suicide Squad" and Robin's suit from the "Batman v Superman" trailer.

Looking closely at it, there appears to be two points of damage from Robin's suit, which coincidentally matched two scars on the Joker's shoulders.

Then there's the scrawl across the suit that said, "Hahahaha Joke's on you Batman."

Inquisitr also pointed out that if Grayson is Suicide Squad's Joker, then a quote from the "Dawn of Justice" trailer makes more sense.

Bruce Wayne told Alfred, "20 years in Gotham, how many good guys are left? How many stayed that way?"

However, not everyone is convinced. Den of Geek said that director Zack Snyder is "a comic book literalist" and the graffiti on Robin's costume is intended to evoke Jason Todd AKA the second Robin, who was beaten to death by the Joker in an exploding warehouse.

All these theories are only making fans more and more excited about the slew of movies from DC's cinematic universe beginning next year.

Until then, all we can do is wait to see which theory is correct.

"Suicide Squad" isn't due to hit theaters until August 5, 2016, but maybe clues can be found beforehand in "Batman v Superman: Dawn of Justice", which will hit theaters a bit earlier - on March 25.