An episode in a series that serves as a sequel to a previous episode. Different from a Two-Part Episode, in that there may be several episodes (if not several years) inbetween the first episode and the one that picks up the plot again. To qualify, it's not enough to simply have an object, setting, or character from one episode appear in another, otherwise any series with a Rogues Gallery would consist almost entirely of Sequel Episodes. If Cop Show has the Main Characters arrest a thief and recover some stolen jewels in one episode, and a later episode has the thief break out of prison and cause some more havoc, that's just a One-Shot Character moving up to Recurring Character status. If, on the other hand, a later episode has the cops discover that the stolen jewels they recovered were actually fakes, and they have to interrogate the thief to find out where she hid the real jewels, that is a Sequel Episode; the plot resolved in an earlier episode is reopened and explored again in a new episode. Obviously this only applies to series where Stand Alone Episodes occur somewhat regularly. If the whole show is one long Story Arc, there's not enough seperating the plot of one episode from another to make labelling it a "sequel" meaningful. However, if a series has multiple Story Arcs, it is possible for a later Story Arc to be a sequel to an earlier one.
- On How I Met Your Mother the episode "Slap Bet" had Marshall win a bet that allowed him to slap Barney in the face five times, as hard as he can, at any moment he chooses. Next season, we got the episode "Slapsgiving", where Marshall decides to dole out one of his slaps on Thanksgiving Day and spends the whole episode putting Barney through a Paranoia Gambit. Then, two seasons later, they gave us "Slapsgiving 2: Revenge of the Slap", where it's Thanksgiving again and Marshall decides to let Ted and Robin slap Barney in his place; once more Barney spends the whole episode tortured by the knowledge of what's to come.
- Buffy the Vampire Slayer had the episode "The Wish" where the vengeance demon Anyanka creates an Alternate Universe where vampires rule Sunnydale. By the end of the episode The Verse is returned to normal and Anyanka is left powerless. Later that season, the episode "Dopplegangland" was driven by Anyanka's attempts to regain her powers, and maybe warp reality back into a vampire run hellhole while she's at it.
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