Over 3,000,000 years ago in the Aigbuth Arms pub, a box with a baby inside was placed under a pool table with just the word Ouroboros written on the side… Returning to the present day, the crew come across a wormhole between dimensions. They go through the wormhole, and meet an alternate version of themselves. Rimmer isn't there, Lister is a Hologram, Kochanski is alive, and Kryten is wearing a gold suit. They decide to exchange information and Kochanski requests that Lister fills a canister up with his sperm, so that she may have a child as her Lister cannot bear children. Unfortunately, Lister's in-law's - the GELFs attack (see Emohawk), and cause a break in the wormhole and Kochanski becomes caught on this side. They eventually manage to escape the GELFs, thanks to Kochanski's navigation. Kryten is jealous because Lister likes Kochanski more then him and is glad when they return to the wormhole to get her back to her own dimension. On a box they found some supplies in, Lister notices has a label "Ouroboros", with a symbol on it: a snake biting his own tail, meaning infinity - a never-ending circle. Lister recognises this as what was on his own box and realises that he is his own father and Kochanski is his mother. He rushes after Kochanski to get the in-vitro tube back before she returns to her reality. Disaster strikes, as the GELFs return and make the break in the wormhole even bigger. Kochanski tries to jump across and misses the other side, falling into a deep black void. While she's falling, Lister rushes back and gets a crossbow and a rope which Kryten happened to have handy, and harpoons Kochanski and pulls her back to his side. 18 months later, Lister takes he and Kochanski's child, and puts him in a box, writing "Ouroboros" on it, so it would remind himself of the sign when the child got to be him, and he would bring back his child, etc... (thetvdb.com)