Craig Boone: At Novac's Dino-Bite Gift Shop.Gained from 75 Speech or flirt with him (Confirmed Bachelor perk) Arcade Gannon: In the Old mormon Fort in Freeside.If you choose to listen to mister house, you can even get a base of operation in the Lucky 38) You can have one humanoid (Raul, Arcade, Boone, Veronica, Cass, Lilly) and one non-human (Ed-e, Rex) at a time. Not only can they fight, but can carry items and some time make quests easier. Throughout your journey you can find allies that are willing to join you in your quests and aid support.
