Warning: this post contains spoilers for "Game of Thrones," including speculation of future events.

Buckle in "Game of Thrones" fans, there's a new fan theory circulating online, and this one might throw you for a loop.

It starts with an older theory, one that claims Ned Stark is not Jon Snow's real father. Known as R + L = J, the conjecture states Jon is the love-child of Prince Rhaegar Targaryen and Lyanna Stark, Ned's sister. Book readers began discussing this idea online as far back as 2006, as evidenced from this thread. The evidence for this is aplenty, as you can see in many posts around the web. If this reveal (which would mean that Jon is heir to the Iron Throne and Daenerys Targaryen's nephew) isn't enough to blow your mind, now there's a new twist:

Jon may have had a twin.

On Tuesday, Redditor ghostchief posted a season six opening scene prediction, which outlined a dramatic scene with Ned Stark rushing to the bedside of his sister painfully giving birth to Jon:

A baby's cry rings out as the septa raises a boy and walks him over to the man and woman.

The dialogue swells and clarifies to her voice, "Promise me, Ned."

Her eyes slowly close.

Ned begins to sob.

He raises his head to sound another high pitch noise coming from the foot of the bed.

A baby girl

The baby boy in the sequence would be Jon, who Lyanna asks Ned to protect before dying from birthing complications. But the twist is the "baby girl" — who is she? The thread does not help much with identifying who Jon's twin is. However, theories that align with this idea have been in circulation for a few years.

Meera Reed, one of the companions who has been helping Bran Stark on his journey north, might be this baby girl.

Meera Reed was last season in season four of "Game of Thrones" with Bran and Hodor HBO

This 2012 post to "A Forum of Ice and Fire" elaborates on the idea: "What if Ned had Howland take Meera back to Greywater Watch to raise Meera as his own and Ned took Jon back to Winterfell to raise because bringing two bastards back would seem suspicious?"

Confused? Let's back up a bit.

In the first book, "A Game of Thrones," Ned Stark has a flashback to a scene known as the "Tower of Joy." Years ago in Westeros, a war was started when the prince, Rhaegar Targaryen, allegedly kidnapped and raped Lyanna Stark — sister of Ned Stark and the promised wife to Robert Baratheon.

The Starks and Baratheons teamed up with other houses to fight and defeat the ruling Targaryen family, killing Rhaegar in the process. After the war ended, Ned went to rescue his sister from the Tower of Joy where she had been living. His only companion on the rescue mission was a man named Howland Reed.

It is widely believed that Lyanna not only went willingly with Rhaegar, but that she was pregnant with his child (or as the topical theory suggests, children). Jon and Meera.

In Ned's flashback, he recalls Lyanna in a "bed of blood" which many take to mean that something went wrong during labor. She dies, but not before begging Ned to promise her something. If Lyanna did produce Targaryen babies, they would be in imminent danger from Robert Baratheon and the other enemies of the Targaryen family.

So it makes sense that Ned would lie, claiming Jon as his own in order to protect him. If there was a twin, she would have undoubtedly been handed over to his only trusted friend present — Howland Reed.

Meera was introduced to readers (and viewers) as Howland Reed's daughter. As noted in Bill Bradley's Huffington Post report on this theory, Meera and Jon Snow look very similar on the show.

The resemblance is due mostly to their dark, curly hair and penchant for wearing fur, but the similarity is there for those that want to believe this theory.

The evidence goes beyond just looks, though. One of the posts from a few years back summed up support for Meera's uncovered identity, comparing her to the other Stark children:

Meera was born in the same year as Robb and Jon, and we know nothing whatsoever about her mother...Meera's physical description is very similar to Lyanna's and Arya's. She's slim and flat-chested, attractive without being traditionally beautiful...The odds of Lyanna dying in childbirth seem more likely if she had twins.

Not everyone is on board with this idea though. Lots of "it's too Star Wars" comments have been made, alluding to the Luke and Leia secret-twin twist that came in the iconic series. More than one Redditor referred to the theory as "solid tinfoil," dismissing the idea as creative but too outlandish to be true.

But others are convinced. According to the Huffington Post's poll, 78% of viewers agree that it's might be true.

No matter where you stand, all "Game of Thrones" fans can agree that this is a fun possibility.