Rumple (Robert Carlyle) is expected to make a life-altering decision in episode 20 of "Once Upon a Time" season 6.

Based on the trailer of the episode called "The Black Fairy," Emma (Jennifer Morrison) will try to convince Rumple to help her win the war against the Black Fairy (Jaime Murray), who also happens to be his mother.

While Rumple appears to be prepared to fight against his mother to finally put an end to all her evil schemes, Emma seems to be unsure if he will stick to his promise since Rumple could always change his mind and revert his loyalty back to his mother even if she abandoned him as a baby.

According to the synopsis of the upcoming episode, the Black Fairy will find out from Rumple's fairy godmother that his destiny has been predicted. This will prompt her to do everything in her power to keep the prophesy from happening. However, the Black Fairy will be forced to make a decision that will forever change both her and her son's lives. However, Rumple is also expected to experience the same problem in Storybrooke based on the episode's description.

Meanwhile, Emma must make sure that she will win the battle against the Black Fairy prior to her upcoming wedding with Hook (Colin O'Donoghue). To do this, the bride-to-be must look for the location of the Blue Fairy (Keegan Connor Tracy) since knows where to find the other half of the magic wand that Hook possesses to finally end the existence of the Black Fairy.

The episode is slated to air on ABC on Sunday, April 30, at 8 p.m. EDT.

Meanwhile, Entertainment Weekly shares that ABC officially revealed that the sixth season of "Once Upon a Time" will end in a two-hour finale on Sunday, May 14. However, the network has yet to make a renewal announcement for season 7.