Reunion and Separation is the seventh episode of the second season of Gundam 00.
Louise's GN-X III advances on Ptolemy 2. Ian urges Saji to shoot but Saji hesitates, as the angry sentences he shouted at Setsuna rang in his head. He doesn't fire, which Ian says is just fine. The Ptolemy 2 swerves out of direction and fires a swarm of GN missiles at Louise. Her suit's right arm is taken out but Andrei blocks the rest. Setsuna is being bested by Mr. Bushido, who slices' 00's shields. Meanwhile, Allelujah tries to reach Marie/Soma but she only responds by attacking him and damages Arios on his right side. With one last bit of strength, he moves his Gundam's arm to grab Soma, determined never to let her go again, bringing both of them down to the ground; Setsuna goes to his last resort: Trans Am and slices Sakigake's left arm. As he goes for the killing blow, the Twin Drives inexplicably overload, stopping him in mid-flight and falls in the ocean. Deciding he's not worth the effort to kill while incapable, Bushido flies away, while his comrades go in for the kill. But they are intercepted by Cherudim and Seravee. A revived Sumeragi orders the bridge crew to fire smoke torpedoes filled with high density GN particles to aid in their escape. This clouds visibility and sensors. Sumeragi then orders 00 salvaged and then a search to look for Allelujah. Onboard, Ian chastises Setsuna for using Trans Am. Saji helps Setsuna repair 00, hoping to to anything to help the Katharon refugees and to atone for sins.
At night, somewhere on the ground, Allelujah wakes from unconsciousness, and goes to find Marie/Soma. She also wakes up and immediately attacks him, pinning him to the ground. But before she could deliver the finishing blow, she starts getting headaches, with the name Marie screaming in her head with flashes of memories with Allelujah. She then wakes as Marie, who remembers Allelujah before losing consciousness.
Sergei personally goes out in search of Soma, so do Louise and Andrei but the latter is recalled, as A-Laws leaves the searching for the regular army.
Another memory flashes in Marie, calling out for Allelujah. Returning to reality, Marie awakes in a tent, which Allelujah had set up. He has checked both their machines, which are damaged beyond operation. They begin to talk about their times since the Superhuman Institute; Allelujah says that when he and his friends escaped disposal, he regretted not taking Marie with him. But the ship they escaped on led to nowhere and they were running out of food and oxygen. Hallelujah emerged, killing everyone to survive; Marie says that Soma Peries was another personality made to restore her five senses and to keep the Superhuman Institute opened. But she considers it a good thing, as she could finally see his face. Allelujah says that there are many things he regretted, such as killing their other comrades five years ago. Marie says that she is the same as him, for as Soma, she killed Hallelujah.
Just then, Sergei had located them. He pulls a gun on Allelujah, believing him to be a danger to Soma/Marie and would drag her into Celestial Being's activities, and hates him for the death of his comrades. Allelujah is willing to accept death, just as long as Marie doesn't get involved with fight anymore. As Sergei prepares to shoot, Marie leaps in the way, but Sergei actually fires in the air. He says that he'll falsify a report that 'Soma Peries' died in honourable combat. Marie thanks the Colonel for not making any unnecessary killings; Sergei remarks that she is not Soma he knew; Marie says that Soma is co-existing with her and says she wishes to be her daughter. That is enough for them to hug. Sergei tells her to stay with Allelujah and be happy with him. Marie salutes Sergei as he takes off, with memories of her time as Soma flashing in her. Allelujah embraces Marie, thanking her for living and giving him a reason to live.
Meanwhile, Lyle and Haro are still searching when Sergei uses a light signal to point them in the right direction. They find Allelujah -- kissing Marie. A report is sent to Ptolemy 2, putting a smile on everyone's faces, including Setsuna. Mileina also shows the image of the kiss, shocking the bridge crew.
Elsewhere, Tieria is informed but jsut then, he meets Regene Regetta, who has his exact same face. Regene explains they share the same DNA, type 0988.