Fallout: New Vegas has a colorful cast of recruitable companions you can travel with. Each of them have their own sidequests that change their endings and reward you with new perks. Unlike Dogmeat in other Fallout games, Rex is a mysterious cyberdog you can travel with.

He comes with the Search and Mark perk. This highlights lootable objects with a green light when aiming down your sights. Rex is acting strangely when you first bring him into your party. Complete the Nothin' but a Hound Dog quest to give him a new brain. This guide will explain what each brain will do to him and help you make your choice.

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Nothin' But a Hound Dog

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You can speak to the King in Freeside to learn about his dog Rex. You need to help the King and his followers up to the G.I. Blues quest to recruit Rex. The King will explain the dog's issues and give you the quest to help him. Speak to Julie Farkas of the Followers of the Apocalypse, and she'll recommend someone named Doctor Henry.

Travel to Jacobstown

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You will need to travel far to the west of New Vegas to reach Jacobstown. Follow the road up to the northwest then through the mountains to avoid cazadors. Jacobstown is a settlement populated by friendly super mutants and nightkin. Be nice to Marcus at the front gate to be allowed in.

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Speak to Doctor Henry at the town's main ski lodge and ask about Rex. He will explain that Rex's brain is very old and experiencing neural degradation. It's up to you to get another brain and have Doctor Henry swap out the old one.

Find a New Brain for Rex

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You have three optional objectives to get a new brain for Rex.

  1. Rey is Old Lady Gibson's sick guard dog near Novac. Offer 700 caps for Rey's Brain. You can get the brain for free if you have 70 or higher Barter skill.
  2. Violetta is a hostile guard dog for a group of violent fiends near the Poseidon Gas Station. You will have to fight her master Violet as well, who is part of the Three-Card Bounty quest given at Camp McCarran. Loot Violetta's brain after you've defeated her.
  3. Lupa is a guard dog for the Ceasar's Legion houndmaster Antony. Enter the Fort during Render Unto Ceasar and ask Antony about the dog. He will demand that Lupa receives an honorable death. You will have to fight Lupa in the arena with no armor and while wielding a machete.

Which Brain is the Best?

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Once you have a brain, you can return to Doctor Henry and ask him to make the swap. Rex will receive the memories of the dog's brain that you choose. Each will give Rex a new perk.

  • Rey - Rex receives the Faithful Protector perk, increasing his attack power by +25 damage.
  • Violetta - The Unshakeable Tracker perk gives Rex +50% movement speed.
  • Lupa - The Blood of the Legion perk gives Rex +10 Damage Threshold making him more durable.

Violetta will be a bad choice for Hardcore playthroughs as he will quickly attack enemies and potentially die before you notice. Lupa is a good fit in Hardcore Mode and storywise, as he easily acclimates to his former life as a legion hound. Rey is the most peaceful and useful for damage. The best brain is whatever accommodates your build and RPG preferences.

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Fallout: New Vegas
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8 /10
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Released
October 19, 2010
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WHERE TO PLAY

SUBSCRIPTION
DIGITAL
PHYSICAL
Checkbox: control the expandable behavior of the extra info

ESRB
M for Mature: Blood and Gore, Intense Violence, Sexual Content, Strong Language, Use of Drugs
Developer(s)
Obsidian Entertainment
Franchise
Fallout
Platform(s)
PS3, Xbox 360, PC
Genre(s)
RPG