Adventure Time Omega is a spinoff series based on Adventure Time. It is based in Eee, northwest of Ooo. The story focuses on Jessie and Mack, two kids who help save people in Eee.
Jessie: She is a 11 year old girl, and the sister of Mack. She tends to get in the way of things, but always helps out. She has a "little" crush on Cool Prince, ruler of the Cool Kingdom. She is also friends with Finn, who moved to Eee with Jake.
Mack: He is the 13 year old brother of Jessie and probably most mature. He built the shack for them to live in after washing on shore. He hangs out with Finn and Jake on weekends, or when all is safe in Eee.
Cool Prince: The ruler of the Cool Kingdom, and friends with Jessie and Mack. Jessie has a crush on him, even though he is 14. He loves to play rock guitar and eat candy. He is a cyborg-human hybrid, he talks human but is hard as metal.
Finn & jake: They moved to Eee after defeating The Lich again, and they still help out people. They are best friends with Jessie and Mack, and also play around in the Cool Kingdom. They help them from the Evil King who hates them.
Evil King: He is ruler of the Evil Kingdom, and is enemies with Jessie and Mack. He owns a cutish help dog Spark, who is charged with lightning. He tries to rule Eee by doing evil, but is always foiled.
BJ: He is the son of Beemo, adopted from a burning store. He was given to Jessie and Mack when he was good enough. He loves games like Halo, Lego games and Spy vs Spy.
Spark: He is the Evil King's pet who is charged by lightning. He tries to help but sometimes ruins the plan.
(I have quit this series, so someone may be able to take over.)