- Main article: Uglies (book)
As an Ugly, Peris was serious, tricky, and even a little sad. He and Tally were very close friends since they were littlies to the point where they cut each other's palms and held hands, sharing blood to mark their bond.
When he turns sixteen three months and two days before Tally and becomes Pretty, Tally feels very lonely. She impulsively decides to sneak over into New Pretty Town and confront Peris, intending to make sure that they are still "best friends forever". He makes her promise to not cause any trouble so she can turn Pretty right on schedule, saying that they'll continue to be best friends forever once they are both Pretty together.
After Tally's new friend Shay runs away to the Smoke and Special Circumstances attempt to blackmail Tally into following her, Peris visits Tally in her Uglyville dorm room. New Pretties very rarely leave New Pretty Town, much less to visit Uglyville, but he does just that in order to encourage his best friend to keep his promise to him by helping the Specials find the Smoke.
- Main article: Pretties (book)
Peris can hardly wait for his best friend Tally to be voted into his clique, the Crims, at Valentino Mansion's costume party. As they both prepare for the bash, they feel just as close as they did when they were Uglies. Later at the party, Tally runs away from Specials by slamming into the bungee-jacket-wearing Peris and clinging onto him as they tumble over a balcony. As Peris shoots back up, his knee whacks into Tally's forehead and cuts her eyebrow. Hiking back to her from the river, Peris teases her for the stunt and calls a warden car so that Tally's cut can be healed. Peris goes back to the party after Tally goes home but excitedly pings her to say that she's been accepted into the Crims.
After Tally and Zane split the cure between them, they decide to show the New Smoke that it worked by breaking apart the floating ice rink above Nefertiti Stadium. Peris reminds Tally to wear her bungee jacket, a little nervous at the stunt they're about to pull, but happily skates around with Tally as he informs her that the Smoke hasn't shown itself since the Valentino bash. But soon enough, Zane gives the order to begin their trick and Peris and the rest of the Crims pour out alcohol from flasks to help thaw the ice. When Zane slams down hard onto the weakened ice in time with the fireworks, the whole rink collapses and takes everyone down with it.
Some weeks later, the Crims attempt to escape the city via a hot-air balloon. Peris, along with Fausto and Zane, rides in Tally's balloon but is the only one alarmed when Tally and Zane attempt to take their interface cuffs off by expanding the metal with heat from the hot-air balloon's flame. Tally realizes that she didn't explain her plan to him, but doesn't have time to elaborate beyond saying that she has special gloves on. Horrified, he can only watch as Tally torches the cuff before finally tearing it free from her wrist. When the red-hot cuff ignites the floor of the gondola, Peris looks ready to jump out of the balloon without bothering to grab a hoverboard first. Luckily, Tally douses the flames with a bottle of champagne before he can try.
Not that he does anyway. When the time comes to leap from the balloon to freedom, Peris refuses to jump after Zane and Fausto. He tries to explain to Tally that although he enjoyed being a Crim and being bubbly, he never expected to actually leave the city. Tally reluctantly realizes that Peris had never gone to the Smoke, had never tangled with Special Circumstances, and had never even gotten in trouble. They have grown too far apart to remain "best friends forever". She reminds him that if he stays, he'll still have the lesions and go back to being pretty-minded, but that doesn't bother him. He likes being bubbly, but he doesn't want to go to the extreme of living in the wild. But the Crims are his friends and he didn't want to argue with them about leaving, unable to really face the fact that they don't ever want to return. He tries to convince Tally to stay with him and continue to be best friends forever, but she tells him that she'll always find a way to escape. He counters that being pretty-minded is better than being Rusty-minded and that maybe the city has good reasons for modifying people's brains. Tally declares that she's leaving and quickly kisses Peris before throwing herself on the rail of the gondola. Peris catches her arm, worrying that she may die and saying that he doesn't want to lose her, but Tally sadly remarks that he already has before flinging herself over the edge.
Despite backing out from the plan, Peris still helps them escape by making the balloon rise, throwing off pursuit by diverting it to himself. He misses Tally and the other Crims and sometimes regrets his decision to stay behind, but ultimately sticks with his choice.
- Main article: Specials (book)
Leaving his interface ring behind with Zane, Peris and the other new Crims distribute the cure. Soon after the armory's destruction, he's ready and waiting to escape with Zane and a few other Crims. Surprised at Tally's new terrifying face, he nevertheless holds his ground under her dismissive glare. He even manages to slightly impress her with his idea to take everyone's rings and tie them to small balloons, making it look as though the Crims are merely taking a lazy hoverboard ride together. They soon make their escape, someone always close to the shaky Zane in case he needs help.
They all eventually arrive at the New Smoke, located within the city of Diego.
After the war, Peris sends Tally a ping explaining that he's left the city because it's no fun being there if everyone's a Crim. He and some other friends are instead gathering up the pre-Rusty villagers that the Smokies freed from the reservations. They intend to teach them about technology and how the world works so that they can help bring the rest of their people out into the world. Peris is also going to learn the ways of the wild from them, such as how to hunt, fish, and live off the land before that pre-Rusty knowledge is lost again.
- "When I got back, the Crims had already voted! They thought it was totally bubbly that real-life Specials were at the party, and our dive off the tower got six hundred milli-Helens from Zane! You are so Crim!"
- "I liked being a Crim and being bubbly. But I never thought we'd get this far. I mean, like, leaving home forever?"
- "I just got caught up in everything. Being a Crim was exciting and you were my friends, my clique. What was I supposed to do? Argue against running away? Arguing's bogus."
- Peris was originally supposed to be a girl named Peri, but author Scott Westerfeld decided to change Peris's gender because it was easier to write "he said" and "she said" during conversations with Tally.
- Peris's flash tattoo is a third eye in the middle of his forehead that blinks in time with his heartbeat.