Find the following eight companions by searching the corresponding locations, then complete the listed task(s) to recruit them. Note: Only one human as a companion is possible at a time. If you recruit a new human companion, you will need to tell them to go to the Lucky 38 Casino so you can swap with him or her later:
Arcade Israel Gannon Location - Arcade Gannon is a member of the Followers Of The Apocalypse with a mysterious past, and can be found in the Old Mormon Fort. Perk - Better Healing allows you to regain 20% more health from all sources such as Stimpaks, Doctor's Bags, food, etc. Upgrade - Hoover Dam help or Tesla Armor as a gift when you complete the quest. Cass Location - Cass (a.k.a. Rose of Sharon Cassidy) is a caravan merchant and the daughter of John Cassidy, and can be found at the Mojava Outpost inside the Mojava Outpost Barracks sitting at the bar drinking. You must complete the "Heartache By The Number" quest to start the process of being able to recruit her. You must then complete the "You Can Depend On Me" quest from Alice McLafferty. Note - Additional quests may come up during these quests depending on the choices you make and how you are playing the game. Perk - Whiskey Rose gives you and Cass a higher damage level when you both drink whiskey. You will also not suffer intelligence loss from consuming alcohol and ignoring the effects of alcohol addiction. Upgrade - Hand Of Vengeance or Calm Heart. The Hand Of Vengeance allows Cass to do 15% additional damage with all guns, and to have better skills with guns. The Calm Heart gives Cass +50 HP, and makes her survive longer during combat.
Craig Boone Location - Craig Boone is a very talented ex-NCR sniper with a grudge against Caesar's Legion, and can be found inside the Dino's mouth guarding the town of Novac after 9 p.m. You must complete the "One For My Baby" quest that he gives you when you talk to him in order to be able to recruit him as a companion. He offers a lot of help if you play on the Hardcore difficulty. He pairs really well with either ED-E or Rex. Perk - Spotter automatically marks hostile targets in the area, which can help at night in case you do not spot an enemy or to differentiate between a friend or an enemy. Upgrade 1 - 1st Recon Beret, which gives you +1 Perception and +5% Critical Chance. You will get this after completing the first quest with Craig Boone. Upgrade 2 - 1st Recon Survival Armor or 1st Recon Assault Armor. The only difference between both armors is cosmetic. You will get this after completing the second quest with Craig Boone.
ED-E Location - ED-E is a prototype eyebot designed for combat and reconnaissance operations, and can be found in Primm. Perk - Enhanced Sensors allow you to detect enemies at an increased range, and enemies will appear on the compass and can be targeted in VATS even while cloaked. This works even better if you use this in conjunction with the Spotter perk from Craig Boone. Upgrade - Enhanced armor or weapons when you complete the quest.
Lily Bowen Location - Lily Bowen is a friendly nightkin and former member of the Master's army, and can be found in Jacobstown. Perk - Stealth Girl improves the duration of Stealth Boys by 200%, and all Sneak Attack Critical Hits do an additional 10% damage. Upgrade - Dialogue about medicine after psychotic breaks or administer medicine in varying amounts to affect the frequency of psychotic breaks and combat damage. Raul Tejada Location - Raul Tejada is a ghoul mechanic and former gunslinger held hostage by Tabitha, the mad leader of the State of Utobitha, and can be found in Black Mountain. Perk - Regular Maintenance slows down the decreasing condition of weapons and armor. It basically lengthens the amount of time you have with a weapon or armor. This can also counteract the negative effects of the Build to Destroy trait. Upgrade - Vaquero or Full Maintenance. Vaquero gives an increased combat ability. Full Maintenance slows down the decreasing condition of weapons and armor by 75%.
Rex Location - Rex, a cyberdog belonging to The King, and can be found inside The King's School Of Impersonation in Freeside. You will either need to pay 500 caps or have a 60 Speech skill level to get past Pacer who is guarding the door. You will get the 500 caps back when you talk to The King inside. You must complete the "G.I. Blues" quest given from The King before you get the "Nothin' But A Hound Dog" quest from him, which is how you will be able to recruit Rex. It takes approximately 40 minutes to complete both of these quests. Perk - Search and Mark allows you to find unequipped chems, firearms, and ammunition within a short distance as well as other items such as hidden safes and hollow rocks while you are using the binoculars. Veronica Santangelo Location - Veronica Santangelo is a disillusioned Brotherhood Scribe, and can be found in the 188 Trading Post. Perk - Scribe Assistant allows you to craft workbench items through Veronica's dialogue. She is basically a portable workbench. She also benefits in close combat skills when you complete the quest.