After an explosive season 4 finale, HBO's epic fantasy series "Game of Thrones" is prepping for yet another season that will unfold the story behind the mysterious bloodline of Targaryens. According to some fan-generated theories, Daenerys Targaryen is not the only dragon rider in the Seven Kingdoms, Ned Stark's bastard Jon Snow and kinslayer Tyrion Lannister are the two remaining dragon riders.

A noble family of Valyrian descent, House Targaryen is the only family that escaped the Doom, a cataclysm of an unspecified nature that is described as the century of blood and chaos that lead to the downfall of Valyria. Leaving from the island called Dragonstone, the family conquered Westeros through Aegon and his sisters with the help of their dragons.

The family ruled the Seven Kingdoms for nearly 300 years until Robert's Rebellion which made Robert Baratheon the new head of King's Landing. Known as dragonlords, Targaryens can tolerate more heat than any humans which made them closer to dragons compared to other men. It was Aegon I who first introduced dragons to Westeros when he conquered it, and kept the dragons for much of the family's reign.

Fans of the book and the TV series have a long wait ahead of them as season 5 of the show is scheduled to premiere next year and George R.R. Martin's sixth book is yet to be published. But fans of the show can help pass their boredom and anticipation by some of these theories that may or may not make sense as it features two of the show's main characters, Jon Snow and Tyrion Lannister.

Taken from A Wiki of Ice and Fire and ASOIAF, here are some of the "Game of Thrones" theories.

Jon Snow

Jon Snow is the Son of Rhaegar Targaryen and Lyanna Stark. To protect his sister from the Baratheons and Lannisters, Ned promised Lyanna to protect her secret to his grave and the King of the North is so honorable that he won't cheat on Catelyn. Showrunners D.B. Weiss and David Benioff even won Martin over when they answered his question: "Who is Jon Snow's mother?"

"While there are a lot of accusations that Rhaegar kidnapped Lyanna, it's also more than possible she willingly eloped with the Dragon Prince. If Lyanna was pregnant with an heir, it makes sense that Rhaegar would leave three members of the Kingsguard - including top Westeros badass, The Sword of the Morning, Ser Arthur Dayne - to protect a pregnant Lyanna at the Tower of Joy. Lyanna was said to be screaming during the battle when Ned "freed" her and was found in a pool of blood, both things that could have been caused by childbirth," according to a theory posted on Yahoo.

"Jon is said to resemble Arya, who is said to look a lot like Lyanna. There was also one of Daenerys's visions in The House of the Undying, where she saw a blue rose growing out of a wall of ice. Lyanna's favorite flower was the blue rose and Jon, of course, was stationed at The Wall as a member of the Night's Watch. When you consider the name of the series - A Song of Ice and Fire - it could mean everything is revolving around Jon, who would be the mix of ice (Stark) and fire (Targaryen)."

Tyrion Lannister

Now known as the kingslasyer and kinslayer, Tyrion is believed to be half-Targaryen. "Tyrion is loathed by his father to the point of being removed as the heir to Casterly Rock, and we know Mad King Aerys had eyes for Joanna Lannister, Tywin's wife. There's also the fact that there are three dragons, and, in theory, you would need three riders (Daenerys; Jon Snow, if he's indeed Rhaegar's son; and Tyrion)," based on the website.