Doctor Who series creator Steven Moffat teased some details that the doctor will transform into a lawless bastard in the upcoming finale episode of Season 9. In addition to that, Episode 12 official synopsis has been released and a brief definition of what a Hybrid is has been mentioned.

Executive producer Steven Moffat teased the Radio Times about the finale episode of "Doctor Who" Season 9. Moffat stated that the newest episode will feature the doctor once he is extremely pissed off, something that the enemies never seen before. With that being said, the doctor will become a mad and bad dangerous bastard and a lawless man.

For the official synopsis for the 12th and final episode of "Doctor Who" Season 9, Carter Matt notes, "If you took everything from him, betrayed him, trapped him, and broke both his hearts... how far might the Doctor go? Returning to Gallifrey, the Doctor faces the Time Lords in a struggle that will take him to the end of time itself. Who is the Hybrid? And what is the Doctor's confession?"

Speaking of the Hybrid, Screen Rant details that a Hybrid is a combination of 2 warrior bloodlines which is capable of going head to head agains the Time Lords. In a past episode, the doctor already admitted that he is half human and half Time Lord. Given that the doctor suffered from grief after the death of his companion Oswald, he is now prepared to purge anyone who will come in his way. 

"Doctor Who" Season 9 Episode 12 is entitled "Hell Bent". The upcoming episode is set to air in December 5, 2015 at 8:00 p.m. on BBC One and 9:00 p.m. on BBC America. "Doctor Who" is a British science fiction TV programme produced by BBC since 1963. The show is created by Sydney Newman, C.E. Webber, and Donald Wilson.