The following contains spoilers from Stranger Things Season 4, Episode 1, "The Hellfire Club," streaming now on Netflix.
Stranger Things Season 4 starts with the Hawkins gang struggling to transition into high school after surviving the traumatic battle with the Mind Flayer at the end of Season 3. Like many nerdy teens, Dustin, Mike, and Lucas don't fit in well with the other high school students, except for the Dungeons & Dragons players of the Hellfire Club, but Lucas believes he may have an in with the popular crowd as a freshman member of the Hawkins basketball team, and it puts him at odds with his dice-rolling best friends.
Lucas understandably doesn't want to be bullied anymore and is hopeful for a chance that he and his friends can have a more normal high school experience, but Dustin and Mike see it as a complete betrayal of their characters. This sets up one of the first character conflicts of Stranger Things Season 4 as Lucas begs Mike and Dustin to get their eccentric, new dungeon master, Eddie, to postpone the game and come to the championship game, but Eddie's persona is just too dynamic and intense for the two other friends to overcome. Mike and Dustin attempt to suggest postponing the game to support Lucas but are instead pressured by Eddie to recruit a new player, and, of course, they end up enlisting Lucas' little sister Erica into the party.
Erica makes a triumph return to Stranger Things to save the campaign, even if it is slightly to Dustin and Mike's dismay. The feisty fan-favorite brings all of her attitude to the DnD table as she goes toe-to-toe with the Hellfire Club ringleader. Mike and Dustin were nervous about how the recruit would be taken, but Erica's fearlessness and "no-nonsense" attitude are undeniable as she puts Eddie in his place (along with everyone else in the room). She quickly shows she is no slouch when it comes to playing DnD.
This episode could have truly been titled "The Dynamic Sinclairs," as both siblings score epic victories before the credits roll. Lucas is relieved of his benchwarmer title when he is pushed into the final seconds of the championship game. As Lucas takes the court, Erica is facing down the fearsome undead wizard Vecna alone, and her party is on the verge of a total party knockout.
Of course, neither sibling misses a beat as Lucas goes on to score the game-winning point for Hawkins and Erica rolls the natural 20 that wipes Vecna off the map (at least in the game anyway). Both are met with joyous praise from all around them, but this moment of excitement is cut short for Lucas as he comes to realize his friends replaced him with his little sister. Lucas, unfortunately, sees his friends exit their session with Erica in tow. It quickly solidifies for Lucas that his friends aren't supportive of his newfound hobbies and potential popularity.
Mike says at the beginning of the episode that he and Dustin never cared to be popular in the first place, so it isn't too shocking that they chose DnD over going to the game. That being said, it is kind of a low blow to replace someone with their sibling, so it also isn't surprising that this moment starts a new rift among the Hawkins gang. Mike and Dustin's choice to ditch Lucas pushes him to further follow his new teammates even if it goes against his own heart. But the friends need to reconcile before the end of the season because they will need a full party, and all of Erica's guts, if they are going to defeat the true Vecna.
Stranger Things Season 4 Vol. 1 is now streaming on Netflix.