The comedian Tré Melvin (known for his gender-bending sketch comedy and viral video parodies) is cast in a teen soap; Brandon Rogers (creator of a suite of twisted YouTube characters) is dropped into a psychological thriller, and Anthony Padilla and Ian Hecox (of the recently split bro comedy duo Smosh) are transported into a fairy tale. In contrast to the often-sincere dramatic writing of the original fan fiction, the show has a “snarky alt-comedy sensibility,” Lon Harris, the showrunner, told me. The YouTube stars, largely comedic performers, are winking at the camera as they step into the romantic-lead roles dreamed up by their fans.

“This is a community that we appreciate, and we’re not mocking it,” Mr. Harris told me. Still: “We recognize that a lot of fan fiction is kind of absurd, and it would be inauthentic to pretend that it’s not at all absurd, or that these are totally rational stories that flow just like any other story.”

That ambivalence is on display in the fifth episode, in which a skeptical Mr. Rogers is summoned onscreen to act out some murder-related fan fiction about him. Mr. Monson warns him that the story doesn’t make much sense because it comes from “the mind of a teenage girl,” but then turns around and chides Mr. Rogers: “If you’re going to disrespect the stories, get out of my split-screen!”

On some level, this is a fitting project: Fan fiction is about recasting the source material, and “FANtasies” adds another layer to the endlessly self-referential YouTube fandom. The results can be unexpectedly charming. There is plenty of fan service here: In one episode, Mr. Melvin dances sensually in slow motion. In another, the Smosh duo asks Mr. Monson, “Wait, is this going to be something creepy,” a story “where we fall in love with each other or whatever?” When he answers affirmatively, the two call out in unison: “Carry on!”

Part of what makes the series work is that YouTube personalities thrive at playing alternate versions of themselves. The jabs at fan fiction as a form are softened by the image of these stars seeming so game in engaging in a bit of performative humiliation. When Ms. Yarchin saw the episode based on her story “Paging Dr. Hart,” she told me, “I was smiling the whole entire time.”