In episode 19 of "Once Upon a Time" Season 5, Regina reunited with her mother and estranged half-sister in a special family reunion.

Titled "Sisters," the episode opened with Hades and Zelena going on a romantic trip somewhere. Initially, the wicked witch thought that Hades was up for something fishy, but the lord of the Underworld ended up getting down on his knee and proposing to her.

As he proposed, Hades told Zelena that he wanted to leave the Underworld and settle in Storybrooke with her, but he feared that the heroes would not let him. Zelena neither said "yes" nor "no," and unfortunately, the proposal was made public through Regina's magic mirror.

Regina told her sister Zelena to decline his offer, but the wicked witch was confident that Hades could be saved. Sensing that Zelena had no plans on listening, Regina came up with a plan to keep the lovers apart through the help of Cora.

According to Cora, the only way to separate the two was to make Zelena forget her feelings for Hades. She revealed that they should get Zelena to drink some water from a mystical river so she could forget her love for Hades.

Back in the Underworld, Cora decided to show up in front of Zelena and apologize for abandoning her. While she did, Regina waited for her chance to make Zelena drink the magical water from the river.

Unfortunately for Cora and Regina, their plan didn't work. It turned out that Zelena knew that Regina was hiding in the other room, so she tossed the water into the flames and was angry at Cora for lying to her again and again. She also used her magic to show them memories of their childhood, when they were still sisters who loved and cared for each other.

Towards the end of the episode, it was revealed that Gold was blaming Zelena for casting a spell on Belle, so he sought the help of Peter Pan to kidnap her. The next episode will see what happens to Zelena after Peter Pan drops a bag on her head.

"Once Upon A Time" season 5 airs every Sunday on ABC.