Stay with the Aliens

The aliens arrive, and they want an earthling to come with them. This is not anything harmful, like To Serve Man. They actually want a human to come with them to show all their wonders. Often this is an old man, who saw the aliens once and was called crazy ever since. So the old man not only gets proven right, but also gets to complete the trip he didn't finish the last time. Yet just as often, it's just someone whom the aliens make their Chosen One. If they return, they may be -- different.

Much like the Undead Tax Exemption with people spontaneously appearing in the records, there doesn't seem to be any legal investigation with someone vanishing off the face of the Earth literally.

Compare I Choose to Stay.

Anime and Manga

 * In the Mega Man NT Warrior anime, Baryl opts to go with Duo.
 * Magical Girl Lyrical Nanoha StrikerS
 * Nanoha Takamichi, by the third season, is living on the planet Mid-Childa and pursuing a career in their military. One wonders if she still has an Earth identity; specifically a Japanese citizenship. I mean, do her family still pay her taxes, or did she get disappeared paperwork-wise? (The TSAB has shown they'd probably be able to do that.)
 * Hayate Yagami of the same series also does this. Given she was a nine-year old living alone and then suddenly has four people living with her who appeared out of nowhere there was likely less paperwork.
 * The main protagonist in DearS in the end.
 * at the end of Digimon Savers.

Comic Books

 * In Nextwave, we see that Aaron Stack wanted to stay... but the cosmic supergods kicked him out, on account of him being a giant #%@#.

Film

 * Close Encounters of the Third Kind: At the climax Roy Neary enters the alien ship, disappears into the light and the ship departs Earth. Which is kind of awkward for his wife and kids.
 * The end of Stargate, although they came to the aliens (who might have been human anyway). An episode of Stargate SG-1 did this with Jackson's grandfather.
 * At the end of Muppets from Space, after Gonzo decides I Choose to Stay, his people take the head of the extraterrestrial investigation agency who had been chasing after Gonzo with them.
 * Mission to Mars. Gary Sinise's character stays behind to go off with the Martians.
 * In Flight of the Navigator, it was accidental, as the ship just was keeping the hero for study, but warping space and time kept him away for eight years.
 * In The Last Starfighter,.
 * Happens in K-PAX.
 * While the final script of Aliens vs. Predator ended with
 * This actually happens at the end of the first arc in the comics. A later arc returns to the idea, and shows the human distanced from the Predators,
 * It also happens in the novel, Aliens vs Predator: Prey. The main character is marked (on the forehead, not the cheek) and taken aboard the ship. They treat her horribly, even after being key in the capture of a queen, so she decides to leave. The mark still works in her favor in subsequent encounters with the predators.
 * Charlie from the Critters films. Subverted in that it's implied he pestered the alien bounty hunters into letting him tag along, although we don't actually see them make up their minds to do so.
 * The children in the 2009 film Knowing. Although they used a godawful
 * Paul: In what is presumably a Shout-Out to Close Encounters, at the end of the film

Literature

 * In Robert J. Sawyer's "Calculating God," the aliens take with them the main character, who happens to be dying of cancer.
 * This is totally subverted in the story "Alien Promises" by Janni Lee Simner,
 * The first book in Bruce Coville's My Teacher Is an Alien series ends with Peter Thompson deciding to go with Bloxholm, since his father's indifferent to his existence and he believes no one will miss him.
 * Dorothy returns home at the end of The Wonderful Wizard of Oz, but in the sequels she eventually decides to stay in Oz and become a Princess. (She brings Aunt Em and Uncle Henry with her.)
 * Warhammer 40,000: At the end of
 * In Andre Norton's Star Ka'at, aliens have been living on Earth disguised as domestic cats. When they decide that humans are about to destroy the world in a war, they all leave; one of them has gotten fond enough of the orphaned boy who's his "owner" that he takes the boy with them, to the disgust of his fellow aliens.
 * In Francis Carsac's Those From Nowhere, a young doctor encounters Humanoid Aliens in a forest and, after helping them fix their ship, agrees to go with them to their homeworld. There, he finds out that they are fighting a losing war against a race of Cosmic Horrors. They need his help to defeat them, as "those with red blood" are the only ones capable of resisting the enemy. After defeating them, the doctor goes home with his Love Interest (from a race of red-blooded Humanoid Aliens with four fingers) in order to put his affairs in order before leaving Earth forever to live on her planet. He also offers the writer a chance to join them.
 * Not just the writer. He returned to Earth specifically to gather a group of open-minded people to go with him to help out his new friends in their war.
 * In Dana Stabenow's Second Star, the aliens—a race of ultimate knowledge-collectors nicknamed The Librarians—were initially attracted by their discovery of a newly-sentient computer system, but when he turns down the offer to go with them, they extend it to the protagonist's Teen Genius niece; she accepts in a heartbeat.

Live-Action TV

 * The companions of Doctor Who. The Doctor seems to have a thing for picking up random humans from Earth.
 * Also inverted in the Expanded Universe. In one story, after the Doctor stops a time-traveling alien tourist business that was mucking about in Ancient Greece and he sends them all home in the last portal their machine could make, one of the aliens decides to Stay With The Humans.
 * Wesley Crusher on Star Trek: The Next Generation
 * And inverted in an episode "First Contact" (not to be confused with the movie), where the aliens refused to join the galactic community but the main alien from the episode decided to go with the humans.
 * Star Trek: The Original Series: The Corbomite Maneuver.
 * John Sheridan in Babylon 5. In more ways than one.
 * Jeffery Sinclair even more so.
 * Sebastian the Inquisitor and Mr Morden are the best examples, because the aliens they stayed with were far more "alien" to humans then Minbari were.
 * The first episode of The Greatest American Hero has FBI Agent Bill Maxwell's old partner saying he's doing this with the aliens that gave Ralph the super hero suit. However, he clearly died earlier in the episode, so its ambiguous if he was simply re-animated or if his lifeless body was being controlled by the aliens so they would have some way of communicating beyond their bizarre radio trick.
 * This trope is wholeheartedly embraced by Cassandra Spender from The X-Files, Agent Spender's mom, multiple alien abductee, and : she is convinced that the aliens preparing to colonize Earth wish only the best for humanity and that they will take a select few (including herself) to their world just before it begins.
 * Allie in Steven Spielberg's Taken. She stays with the aliens after they decide The World Is Not Ready for her.

Video Games

 * Hanako of Disgaea 2: Cursed Memories was born after her parents were turned into demons due to Zenon's curse; so she has been a demon all her life. Adell's success turned her into a human; but it she didn't want to be one; so left Veldime with Etna in order to find a way to become a true demon.
 * In the DLC for Disgaea 3: Absence of Justice, she appears as her previous incarnation, so she apparently succeeded.
 * She uses Time Travel to join the cast as DLC in the PSP remake to show off her becoming a Demon Lord.
 * The entire ending Playable Epilogue of Lunar 2 had Hiro looking for a way to follow Lucia after her But Now I Must Go ending. He succeeds and goes to Earth to be with her as she terraforms the planet.
 * In Soul Nomad, when Penn is given a chance to return home with his father Thorndyke, he chooses to stay with the Nereids. He's still proud of the fact that his dad is a renowned hero though.

Web Comics

 * Mrs. Primrose, Roofus the Robot, and  in The Inexplicable Adventures of Bob. Dean Martin (no, not the singer) asks for the same favor, but Princess Voluptua turns him down.

Western Animation

 * In the Invader Zim episode "Vindicated," counselor Dwicky learns at the end that the kid he's been patronizing has been right all along, there are aliens, and one's trying to take over the earth! He's then given the opportunity to go joyriding with another set of aliens, which he gleefully accepts, leaving the task of defending the earth from hostile invasion in the hands of an eleven-year-old. He also takes the video camera with documented proof while he's at it. Whoops, his bad!