All companions grant perks upon your character and they all have a quest to fulfill that upon completion allows you to upgrade them. But how do you know which is best for your build? What's the best way to develop them? Arcade: Better Healing perk. Do you in the end have him fight alongside the remnants or stay with the followers? Boone: Spotter perk. Which is better, the survival vest or assault vest? Do you have him become repentant or bloodthirsty? Cass: Whiskey Rose perk. Which is better, Calm Heart or Hand of Justice? Rex: Which Brain is best? Ed-e: Increased Detection perk. Do you upgrade his armor or his weapons? Is it better to take him to the brotherhood or the followers? Lily: Stealth Girl perk. How much of her medicine should she be taking? Veronica: Scribe Bench Perk. Should she stay with the brotherhood or join the followers? Is it better to increase her attack rate or her damage threshhold? Do you give her Elijah's holodisc? Raul: Half Maintenance perk. Should he return to his gunslinging ways which increases his rate of fire with lever action weapons or focus more on better maintenance?