The season finale of “Game of Thrones” always has a few twists, but many fans think they’ve figured out one plot point in Sunday’s episode. Several people agree that a popular fan theory, called R+L=J, will be revealed as the truth in the Season 6 finale.

The theory, which has been around since well before the HBO drama even existed, states that Jon Snow (Kit Harrington) is actually the son of Rhaegar Targaryen and Lyanna Stark. Some believe that Rhaegar kidnapped and raped Lyanna while others think that they were actually in love. When Ned Stark (Sean Bean) went to rescue his sister, he found her in a pool of blood. In  Lyanna’s dying words, she asked him to keep a secret. The theory is that Lyanna asked Ned to raise Jon as his own and keep his true parentage secret.

The “Game of Thrones” cast and crew haven’t confirmed the theory, but they haven’t denied it either. Earlier this season, Bran (Isaac Hempstead Wright) went back and saw his father going to the Tower of Joy to save Lyanna, but the vision ended before Lyanna was shown. Actor Eddie Eyre, who played Gerold Hightower in the Tower of Joy flashback earlier this season, seemed to hint that the finale might return to that moment in time.

HBO has been vigilant about keeping spoilers locked down this year. They’ve nearly eliminated advance press screeners. They haven’t even released a vague synopsis hinting at what will happen in the finale, titled “The Winds of Winter.” Yet, that hasn’t stopped fans from assuming that the “Game of Thrones” Season 6 finale will confirm the R+L=J theory.

It seems like there will be some outrage if HBO doesn’t confirm Jon Snow’s parentage Sunday night, but that’s not the only thing that could leave fans yelling at their TVs. The promo video for the finale, seen at the top of this page, makes it clear that Cersei (Lena Headey) and Loras’ (Finn Jones) trial will be a big part of the episode. The outcomes could upset fans.

The “Game of Thrones” Season 6 finale airs Sunday at 9 p.m. EDT on HBO.