There Are several possible Companions added as the story progresses. You begin the game with Innocence Smith a fellow prisoner you save in the shower. You can have only one companion at a time, some quests make exceptions and allow two. They will comment on the story.
Innocence Smith: a young an innocent boy who is a new prisoner at Camp 19. With his & others help Roy & Innocence are able to escape. He joins the Resistance.
Courtesy: A temporary Companion during a quest to kill the moles infesting a cave.
Sobreity: A temporary Companion during a quest to kill the moles infesting a cave.
Mary: The apprentice & lover of Sean Mancer. After killing Sean she will track you down, when confronted by soldiers she overloads. Roy rescues her and takes her back to his place. Roy then can either kill or ally with her. A potential romance option.
Tenacity Williams: A bounty hunter hired by the Technomancer Generosity. After beating him and his dogs Roy can either kill or ally with him.
If you join Honour GrantEdit
Devotion the ears and hands of Honour Grant. She becomes an ally. A potential romance option.
General Honour Grant: The leader of his faction and a temporary Companion during the assault on The Source to stop Dowser Wisdom.
If you join the ResistanceEdit
Judy one of the leaders of the Resistance. She becomes an ally. A potential romance option.
Marco: A leader of his faction and a temporary Companion during the assault on The Source to stop Dowser Wisdom.