Supernatural season 13
Sam, Dean and Castiel in Supernatural season 12 finale The CW

Supernatural season 12 finale ended with the tragic death of our beloved angel, Castiel. However, Misha Collins, who plays the character, has admitted that he is returning for season 13, but the question remains as to, how and who will resurrect the fan-favourite angel.

Collins revealed at a convention in Rome, Italy back in May, "I think we will see Cas again, but the question is, what [does this death do] to him? That is, I think the one to wonder about."

Castiel has been killed off and brought back to life several times in earlier seasons. In season 4, he was killed by Raphael, and was later resurrected by God. He then joined Sam, Dean and Bobby Singer in the fight between Heaven and Hell. Later he was killed by Lucifer in season 5 finale, and bought back to life by God. Judging by his past, it looks like God aka Chuck may return to bring back the trench-coat wearing angel.

However, a Reddit user thinks that Jack aka Nephilim – the son of Lucifer– may bring back the angel. A user posted a fan theory on the page which states, "Jack will bring Cass back. It was said over and over that Cass will be his protector. Since jack chose him I think he will want Castiel back. Nephilim are more powerful than most entities in the supernatural."

The fan theory believes that the Nephilim may be an ally of Sam and Dean in season 13. "Yes Amara needed souls to grow but Jack is not an ordinary Nephilim, he is the son of Lucifer. An Archangel hybrid. I believe he will have the power to defeat Lucifer and will be a surprisingly good ally for Sam and Dean."

Another user posted his own version of fan theory, which suggests that supernatural season 13 plot will revolve around Jack and portals to other world. "Season 13, I think Jack will continue to be involved and a fair amount of episodes will revolve around issues to do with other worlds, portals to other worlds being opened up and either trying to stop Jack, or maybe trying to get him on their side to get Mary back and maybe to resurrect Cas, " the user explained.

Season 13 of Supernatural will return on Thursday, 12 October on The CW Network.