Comical, wise-cracking, loud-mouthed, and also funny, Richie's loud mouth and foul language get him into trouble most of the time. He always seems to be a real chatterbox, thus some of his friends tend to say to him "Shut up, Richie." most of the time. As a result, he is, ironically, the class clown of the group.
As summer starts, Richie, Bill, Eddie, and Stan talk about how they're going to spend their summers. Bill enlists their help to investigate the Barrens, believing his brother, Georgie, who was killed by Pennywise last October, is still alive. They are then harassed by Henry Bowers and his cronies.
At the Barrens, Bill and Richie enter the sewers, but Stan and Eddie are reluctant to follow, because of the "grey water", which Eddie says is "piss and shit". Richie picks up a stick and sniffs it, and teasingly says "Doesn't smell like caca to me, Señor.", and uses it to pick up a piece of a trash bag, which he throws at Eddie. Suddenly, Ben Hanscom, injured after his recent encounter with Henry Bowers, appears. They take him to an alley where Richie keeps him company while Bill, Eddie, and Stan collect some supplies for his injuries, with Beverly's help.
The next day, when Bill, Ben, Eddie, Stan, and Richie go swimming at the quarry, they are suddenly joined by Beverly. As they are drying off, Richie examines Ben's research on Derry; he explains that Derry is different from all the other towns he has been to, that people die or vanish six times the national average. The six then go to Ben's house to further piece together the town's dark history. When Beverly summons the boys to her place after her bathroom was made into a bloody mess, Richie is left to keep a lookout should Beverly's father return.
After defending Mike Hanlon from Bowers by engaging in a "rock war" with him and his cronies, he joins the group. Meanwhile, as kids continue to vanish, Ben explains that he pieced together the tragic events from the past and concluded that these terrible things only happen every 27 years. Realizing they are being stalked by the same creature, the clown who killed Georgie, they track him to the Well House at 29 Neibolt Street.
As Bill goes to the Well House to confront It, Beverly, Richie, Ben, Eddie, Stan, and Mike try to stop him; Bill points out that nobody else is going to take action. Stan suggests that some of them should keep a lookout in case anything bad happens. Richie, Eddie, Ben, Stan, and Mike volunteer, but Richie and Eddie end up going inside with Bill while Beverly, Ben, Stan, and Mike wait outside. Richie panics when he sees a Missing Kid poster with his picture and description on it. Bill calms him down and explains that It is playing tricks on him. As they go upstairs, the three are separated, and Eddie and Richie are attacked by Pennywise. They reunite with the others and fight off Pennywise.
After Eddie's mom blames them for her son's broken arm, the other six begin to argue about their incursion in the Well House; Richie tries to convince Bill to try to save himself so he doesn't get killed like Georgie was, but Bill punches Richie in the face after he pushes him. Beverly breaks up the argument, explaining that the reason they're still alive is because they fought Pennywise together. Richie says that he plans to keep it that way, and goes to get his bike, angrily pushing past Bill; Stan, Ben, and Mike also defect from the group. Days later, Richie is at the church, attending Stan's bar mitzvah, while Ben and Mike are back to spending time in the library and working on the farm. Bill and Beverly, on the other hand, are spending lonely days at home, not on speaking terms with the others. Eddie, meanwhile, is spending his time cooped up at home.
In August, after Bill drops by Beverly's apartment, only to discover she has been taken hostage by Pennywise, he goes to look for the others, starting at the movie theater, where Richie is playing Street Fighter. Richie is still angry with Bill, to the extent that he is pretending to be beating him up in the game, but when Bill tells him about Beverly's abduction, Richie, horrified by the bad news, forgets his anger towards Bill.
Reuniting with the others, the six go back to the Well House, down the well and into the sewers, but are attacked by a maniacal Henry Bowers, lose track of Stanley, and get separated from Bill after he sees a shade of Georgie. They follow his trail and find Beverly, who has gone into a trance after seeing It's true form, inside Pennywise's hideout. Ben, Mike, and Richie work together to pull Beverly back down to the ground; Richie expresses amazement when Ben kisses Beverly, bringing her out of her trance, and embraces the two when they recite the poem from the postcard.
Meanwhile, Bill catches up with "Georgie", and after a conversation, he realizes it's a trap and shoots him, revealing him to be Pennywise in disguise. The seven attempt to fight Pennywise, but he overpowers the others and grabs Bill, and tries to make a deal with them that he will spare them if they surrender Bill to him. Bill urges them to leave and apologizes for putting them all in danger. Richie admonishes Bill for all the trouble he put him and the others through, then picks up a baseball bat, and declares that he is now willing to fight to the end while bashing Pennywise with it. After defeating Pennywise, when Bill finds Georgie’s tattered raincoat among the missing children’s belongings, and is devastated by the truth that his brother is dead, Richie sympathetically pats him on the back, as he, Beverly, and the others join Bill in mourning for his brother.
In September, as Bill insists that they make a blood oath that if Pennywise returns, then they will return to finish him off, Richie willingly agrees, and is the fourth to leave.
It: Chapter Two
After the events of the summer of 1989, Richie grows up and becomes a comedian in Los Angeles. Over the course of the two decades, the events from his childhood have become nebulous, so when he gets a phone call from Mike to return to Derry due to Pennywise reappearing, he’s not sure why Mike is summoning him and the others back.
Initially, to him and some of the others, it seems like it’s just a reunion, but when their fortune cookies mention Stanley’s suicide, and their memories of two decades ago start to come back to them, Richie begins to think about leaving, as does Eddie, until Beverly and Mike remind them of the vow they made to vanquish Pennywise if he ever returned, and that they’ll die if they fail to keep the vow. With that, Richie agrees to stay. Little do they know, Mike has spent the past two decades doing further research on It.
After finding out about the Ritual of Chüd, which can annihilate Pennywise for good, and that they just need to find items from their past, Richie concludes that the items they seek may be hidden all over the town, so he suggests splitting up to search for them.
Richie and Bill have been good friends since their childhood. However, Richie's argumentative nature can sometimes lead to fights between them.