Warning: This article contains SPOILERS for Abbott Elementary season 4, episode 9, “Volunteers."
While the first half ofAbbott Elementary’sIt’s Always Sunny In Philadelphiacrossover was successful, the sitcoms did leave one character out of the episode for a clever reason.Abbott Elementary’s cast of charactersis reliably hilarious, and the antics of Mr. Johnson, Principal Ava, Melissa, Barbara, and Jacob would be fun without any outside help. However,Abbott Elementaryseason 4’s disappointing ratingsprove that the mockumentary needs to drum up some publicity. Despite stellar reviews, the workplace sitcom is struggling to stand out among ABC’s scripted offerings from the 2024/2025 season.

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The Abbott Elementary & It’s Always Sunny In Philadelphia crossover had hilarious character interactions, but it hid callbacks in its witty writing.
This is whereAbbott Elementary’sIt’s Always Sunny In Philadelphiacrossovercomes in. The event, whichAbbott Elementarycreator and star Quinta Brunson promised would be “Historic,” sees the gang from the long-running FX sitcomIt’s Always Sunny In Philadelphiavolunteer at the eponymous school as part of their court-mandated community service. Season 4, episode 9, “Volunteers,” began with the faculty welcoming their new volunteers but, before long, Dee, Charlie, Mac, and Frank were causing all manner of chaos in the school. However, eagle-eyed viewers will note one series regular was missing from that lineup.

Why Dennis Barely Appeared In Abbott Elementary’s It’s Always Sunny Crossover
The It’s Always Sunny Star Refused To Be Filmed
Glenn Howerton’s Dennis barely appeared inAbbott Elementary’s crossover withIt’s Always Sunny In Philadelphia,even though he is one of the latter show’s main characters. This was effectively explained away in-universe when Howerton’s character immediately noticed the documentary team filmingAbbott Elementaryand decided that he would not give his consent to appear on camera. In reality, Howerton had little time to appear in the episode as he was simultaneously filming the Netflix seriesSirensduring production.Abbott Elementary’s executive producer Patrick Schumacker toldEntertainment Weekly, “We had him for half a day, so we had to build that in.”
Fortunately,Abbott Elementary’s mockumentary setupmeant that this twist felt entirely believable. While all theIt’s Always Sunny In Philadelphiagang are amoral, Dennis is arguably the most outright villainous of the rotten lot. As such, it makes perfect sense for his paranoid, suspicious character to want nothing to do with the documentary crew. This is not even the first time thatAbbott Elementaryseason 4 used its mockumentary setup to establish a storyline. Earlier in the season, a parent instigated a fight with Gregory after he was offended by the teacher’s straight-to-camera asides.
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It’s Always Sunny’s Abbott Elementary Crossover Arrives In Season 17
What makes this absence clever is the fact thatDennis’s limited role in “Volunteers" sets him up for a much bigger role inIt’s Always Sunny In Philadelphiaseason 17’s half of the crossover.As one ofIt’s Always Sunny In Philadelphia’s showrunners, Rob McElhenney, toldThe Los Angeles Times,“When you see the ‘Sunny’ episode, you’ll realize why we did that with Dennis.” This approach is ingenious for two reasons. For one thing, it means thatIt’s Always Sunny In Philadelphia’s half of the crossover event won’t merely be a retread of the events of “Volunteers,” albeit from a new perspective.
Chris Perfetti
Jacob Hill
Although it would be fun to seeIt’s Always Sunny In Philadelphiare-stage the episode’s story, complete with the FX show’s looser censorship and more R-rated humor, this would still feel repetitive. Instead, Dennis’s role inIt’s Always Sunny In Philadelphia’sAbbott Elementarycrossoverwill feel entirely new and fresh. Furthermore, “Volunteers” was already jam-packed with four storylines. There simply would not have been any screen time for Dennis if the episode had included him, sinceAbbott Elementaryneeded to focus on Dee trying to steal Gregory from Janine, Ava and Mac’s plot, and Melissa and Barbara teaching Charlie to read.
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Throw in the rivalry between Mr. Johnson and Frank as they argued over how to rid Abbott of possums and the episode was almost overfilled before Dennis was even mentioned. Dennis’s nastiness is central toAlways Sunny In Philadelphiaand, whenIt’s Always Sunny In Philadelphia’sAbbott Elementarycrossoverwas first announced, he was the biggest concern. Dennis was always going to be the hardest character to integrate into the lighter, warmer show.
The darker FX show can now explain what Dennis was up to throughout “Volunteers” without completely altering the tone of Abbott Elementary.
As such, it makes perfect sense forIt’s Always Sunny In Philadelphia’s half of the crossover to center DenniswhileAbbott Elementarysubtly sidelined him. The darker FX show can now explain what Dennis was up to throughout “Volunteers” without completely altering the tone ofAbbott Elementary, which is fundamentally a less cynical series. As such, the creators ofAbbott ElementaryandIt’s Always Sunny In Philadelphiamanaged to make the most of their crossover by wisely saving Dennis’s story for the second episode in their shared line-up.