Rumple (Robert Carlyle) will finally discover the reason why his mother abandoned him. Meanwhile, the Fiona (Jaime Murray) is out for a battle, and Regina (Lana Parrilla) might be one of the casualties.

On the next episode of "Once Upon a Time" season 6, titled "The Black Fairy," Fiona's past will be told, revealing the true reason why she chose to abandon his son. Based on the synopsis, it appears that her reason for leaving him is tied to his future.

"In flashback, after Rumple's mother, Fiona, learns from his fairy godmother that his destiny is prophesized, she does everything in her power to keep it from happening. Ultimately, Fiona will have to make a decision that will change the course of both their lives forever. Meanwhile in Storybrooke, Rumple faces a similar dilemma," the episode listing on The Futon Critic reads.

However, the Black Fairy's past does not change who she is now, and Emma (Jennifer Morrison) is still determined to defeat her once and for all.

In the episode 19 promo, Emma wants to make sure that Rumple is on board with their plan because it's his mother that will be harmed. Rumple coldly tells Emma, "I won't shed a single tear."

Meanwhile, the Black Fairy might be victorious in killing one of the characters in Storybrooke, which might be Regina.

In the episode promo, Regina says, "The thing about battles is not everyone makes it through." Later on, she is seen being zapped by the Black Fairy.

Will Regina be making the ultimate sacrifice of giving her life to save all of Storybrooke?

Aside from Regina, it appears that the Black Fairy will also take the Blue Fairy (Keegan Connor Tracy) hostage, as seen from the episode 19 photos from BuddyTV.

"Once Upon a Time" season 6 airs every Sunday night at 8 p.m. EDT on ABC.