1. Someone Spots Nessy
Unable to resist the lure of Scotland's favorite aquatic monster, Marshall sees a post on a Nessy forum and he follows it, promising Lily he'll be back in a week, tops. He's not heard from for 10 years.
2. He Moves Back To Minnesota
Sure, Marshall thought he was fine with raising his kid in New York, but one night, during a late-night feeding, he catches the news and immediately hops online to find cheap plane tickets back to the safety of his hometown.
3. Marshall Never Existed
Ted was so lonely during his college years he invented an imaginary best friend, and even when he meets real friends in the city, he isn't ready to let go. Only when he meets his future wife is he comfortable admitting that his Marshall is only a delusion.
4.The Rest of the "HIMYM" Crew Moves
Marshall and Lily are loving Long Island, but after Robin and Barney get married they decide it's time for a drastic change of scene and move to Japan. Ted, always up for grand, irrational moves, follows. and the show's ninth season takes place mainly in a sushi dive in Tokyo without the Eriksens.
5. The Cockamouse Returns
The cockamouse comes back, and it's angry. The injuries leave Marshall so disfigured he needs extensive plastic surgery that leaves him unrecognizable. In others words, Segel leaves, Eriksen stays.