Joe Warren is the only named bloater in the game. He lurks in the spore-filled lower floors of the dormitory at the University of Eastern Colorado, and you have to kill him to collect Warren's Firefly pendant in The University.
In the Go Big Horns section, Ellie and Callus wait at a locked gate while Joel enters the nearby dormitory. Joel drops into the infested lower levels, where Warren and the clickers are.
Kill the clickers quietly first, then burn the bloater down with Molotovs and the flamethrower you pick up in this chapter. Loot the pendant before leaving through the door blocked by a vending machine, because the area seals behind you.
Warren charges as you force the barricaded doors open, bangs on them briefly, then disappears. Ellie later asks if the infected in the dorm were Fireflies, and Joel says he does not think so, even if you are carrying the pendant.
Callus
Callus is the horse Joel and Ellie ride from Jackson County to the University of Eastern Colorado and beyond. He first carries Joel when Ellie runs off in Tommy's Dam, and Ellie names him on the road to the university.
Ellie Williams
Ellie Williams is the 14-year-old girl Joel is hired to smuggle out of Boston, and your companion for most of The Last of Us Part I. She was bitten weeks earlier and never turned, so the Fireflies believe her immunity could lead to a vaccine. You play as her in the winter chapter and in the Left Behind DLC.
Joel Miller
Joel Miller is the man you play for almost all of The Last of Us Part I. A hardened smuggler in the Boston quarantine zone, he takes a job escorting 14-year-old Ellie out of the city, and the drop-off turns into a year-long trip across the country to find the Fireflies.