Kyle is a father from the Pittsburgh suburbs who joined Ish's community in the sewers. In The Suburbs you learn his story from the Looting note and the Cornered note, and Ish mentions him in the Rain catcher note.
Upon leaving the sewers, enter the first brick house and go to the back-left bedroom upstairs; the note is on the bedside table. Kyle writes about gunfire from the Carsons' windows, his family huddled in one room, and a skinny stranger who offered them a safe hidden hideout because Kyle has kids. Joel remarks that following him was not a good idea.
In the sewer utility room near the rain catchers, Ish thanks Susan for the idea and warns that Kyle is making his meatloaf again.
After the runner and clicker ambush in the sewers, go up the stairs and through the door on the left. The note sits on a bench near the bodies in the corner. Kyle writes that he is trapped with some of the children, infected are at the door, and he will make it quick if it comes to that.
Kyle killed the children and then himself rather than let the infected reach them. On the floor by the door he left a message that they didn't suffer, and Joel can only mutter at it.
Henry
Henry is a young survivor from Hartford who is trying to get his little brother Sam out of hunter-held Pittsburgh. He and Joel get off to a bad start in a brawl, then team up to escape the city, and he fights beside you through the end of Pittsburgh and The Suburbs.
Ish
Ish is a survivor you never meet in person: you learn his story from a trail of notes in The Suburbs, from his wrecked fishing boat on the riverbank to the sewer camp he built under Pittsburgh. Picking up his notes in order tells how one lonely man built, and lost, a community.
Sam
Sam is Henry's 13-year-old brother, a quiet, anxious kid who becomes Ellie's first friend her own age on the road. You travel with him from the hideout in Pittsburgh through the sewers and suburbs in The Suburbs.
Susan
Susan is Kyle's wife and one of the founding families of Ish's sewer community under Pittsburgh. In The Suburbs she appears only in notes: the Rain catcher note written to her and the Survivors note written about her.