We met several residents from The Hilltop Colony in Season 6, but Kal has yet to make an appearance on the show.
He debuts in Issue 95, and patrols the metal walls protecting Hilltop. He’s good friends with Jesus, or so we think.
Just ahead of the All Out War arc, Jesus tells Kal of the plan to take Negan down, but later finds out Kal plans on informing The Saviors of the attack in advance. Jesus eventually convinces Kal The Saviors need to be defeated if they want to live in peace, and Kal agrees to help.
Later, Kal is able to alert the others of the incoming Savior attack on The Hilltop, and he attempts to stop the attack, verbally warning Negan. Negan ignores his warning and orders him to be shot; he is then shot in the head by an unnamed Savior in Issue 123.
Brianna is a resident of The Hilltop Colony who makes her first appearance in Issue 109.
She sees Maggie Greene crying at Glenn Rhee’s grave and tries cheering her up. Brianna’s lost people in the apocalypse too, including her husband, parents, siblings, a boyfriend, and even her daughter.
She plays a crucial part in Maggie’s post-Glenn life, helping her understand that death, although sad and terrible, is a part of life and is natural; it isn't something we need to be uncomfortable to talk about. She and Maggie become good friends, and both are still alive in the comics.