The relationship between Rob McElhenney’s many comedy shows is more incestuous than whatever Barbara thought Dennis and Dee were doing back in Season Two.

As McElhenney’s second beloved comedy series Mythic Quest approaches the end of its fourth season, AppleTV+ has announced that it has given the show a greater commitment than Ian Grimm can give to his own son. Last week, AppleTV+ released the trailer for Side Quest, a four-part anthology miniseries that the streamer is marketing as an “expansion” to the Mythic Quest universe. The workplace comedy about a World of Warcraft-style multiplayer video game will use Side Quest to explore “the lives of employees, players and fans who are impacted by the game in an anthology format,” according to the streamer, with special attention paid to the Mythic Quest family in Philadelphia, Pennsylvania, apparently.

Immediately after the trailer for Side Quest dropped, fans of...