Who is Sister Jo AKA Anael on Supernatural and what is her backstory? To the disappointment of Supernatural fans the world over, the long-running fantasy drama will soon come to an end. The much-hyped fifteenth and final season has whipped up a lot of fan speculation as to which characters from past seasons of Supernatural might make a return before the last episode airs.

Showrunners Andrew Dabb and Robert Singer have confirmed the return of several Supernatural characters, including demon hunter Eileen Leahy (Shoshannah Stern) – despite being killed by hellhounds during season 12 – and witch Rowena McLeod (Ruth Connell), who has already returned to help the Winchester brothers in season 15. The final season will also see the long-awaited return of Adam Milligan (Jake Abel), the third and youngest Winchester brother who was last seen in Supernatural’s season 5 finale.

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One character whose possible return and current fate remains unknown is Sister Jo, or Anael to call her by her real name. Played by Jensen Ackles’ (AKA Dean Winchester) wife Danneel Ackles, Anael was first introduced in the Supernatural season 13 episode “Devil’s Bargain.” A low-ranking angel, Anael was once an apprentice to fellow angel Joshua (Roger Aaron Brown/Paul Barton) who became disenchanted and took a job in Heaven as a lowly soul counter. Never content as an angel, she found a new lease of life when she was expelled from Heaven after the Fall of the Angels.

Sister Jo waits for patients inside one of her healing tents in Supernatural

In need of a human vessel, Anael took over a woman’s body in exchange for healing her dying husband and took on the alias of faith healer Sister Jo. As one of the few remaining angels Anael became a target for Supernatural's Lucifer who tracked her down and was planning on killing her for her angel grace. Instead, Anael allied with the archangel by offering herself as a constant source of angel grace and was his second-in-command when he became ruler of Heaven. She soon got sick of Lucifer’s whining and daddy issues with God, however, and returned to Earth after he broke his promise to repopulate Heaven with angels.

Anael popped up again in Supernatural season 14 posing as Sister Jo again and proved useful to the Winchester brothers and Castiel (Misha Collins) when she warned them of Michael’s nefarious plans. Later, her knowledge of Joshua came in handy when she helped Castiel attempt to contact God. While Sister Jo/Anael has yet to show up in Supernatural season 15, the final season is currently only a quarter way through its run so there’s the possibility she could return.

Next: Supernatural Season 15: [SPOILER] Deserved A Better Death Scene