Rex (Fallout: New Vegas)

Rex (full designation of Cyber-Hound Mk. III, LEO Support Model, Serial Number B955883) is a 209 year old cyberdog living in Freeside in 2281. He is owned by the King. He hates rats and will immediately go for one if he sees one. He also doesn't like hats, or people who wear them (he will occassionaly bark at people wearing hats), and it's unknown why, although the King says it might be because "hats" rhymes with "rats".

Background
Rex is a cybernetic dog that has been around since pre-war times. Specifically born in 2072, He was used by the Denver Police Department. Since then, he's been the loyal pet of The King in Freeside. He may have once been owned by Caesar, as Antony notes to the Courier that Caesar used to own a cyberdog. Also, there are red bulls painted on Rex's sides that are identical to the Caesar's Legion standard. In case of his death, his end sequence mentions that he was part of the Legion for some time before reaching Freeside. Capable of sniffing out loot and taking a large amount of punishment, he will join the Courier during the quest Nothin' But a Hound Dog. If the quest is completed, Rex can become a permanent Companion.

Four different dog brains can be used to complete the quest Nothin' But a Hound Dog. They are:
 * Lupa's Brain from The Fort, which increases Rex's health by 100
 * Rey's Brain, which increases Rex's Attack
 * An NCR Guard dog brain, which grants no additional effect
 * Violetta's Brain (from the quest Three-Card Bounty), which increases Rex's speed

Inventory

 * Rex has no ranged attacks, although his melee attacks can knock down an enemy temporarily.

Appearances
Rex appears in Fallout: New Vegas.

Bugs

 * If Rex is implanted with Rey's brain, Rex may run away in combat.


 * If you dismiss Rex during "Nothin' but a Hound Dog", when he is theoretically on loan to you and not a permanent companion, he may disappear and not return to The King. He may eventually show up after traveling to Doc Henry and speaking to him about Rex.


 * When you tell Rex to wait at the Lucky 38, he can sometimes dissapear and not be found in any of the rooms at the Lucky 38 he will be with the king once you find him he will bee-line to the 38


 * While you may be able to get Rex as a companion, you will not receive the mission Nothin' But a Hound Dog. Subsequently you will be unable to repair Rex's brain.


 * After replacing Rex's brain, he may become immobile.


 * When asked to wait, Rex may disappear after the player leaves the area. Npcs will still make remarks to you as if he was there.This can be fixed by waiting 3-5 days.If this happens during "Nothin but a Hound Dog" you will have to wait to be able to finish Guess Who I Saw Today, if Rex is not returned by the time Lily needs to be tested and you have gotten a brain, Lily will not be tested until Rex receives his new brain.


 * If your timescale is something other than 30, and Rex walks up to you after replacing his brain in Nothin' But a Hound Dog, then your game will freeze.


 * After replacing Rex's brain with Lupa's, his health was set to 540/440 (440/440 being the default). Upon taking damage that reduced his health beneath 440, it could not be restored past 440. There is no known way to fix this bug.


 * If Rex is with you when you talk to Corporal Sterling in Camp McCarran then he will attack the First Recon group. This is either a bug or due to his dislike of hats.


 * During combat, Rex might chaotically run around from-and-to foes while not attack.


 * When knocked unconscious by the Courier, at times Rex will randomly shoot hundreds of feet into the air (Similar to a grenade going off).


 * After Rex joins you, he will sometimes refuse to attack regardless of what state or setting you choose for him. He will continue to remain passive throughout the game.  There is an easy fix for this, bring up the console with the ~ key, click on Rex, then type in "Kill"  After Rex dies, bring up the console again, click on Rex, then type "Resurrect" and Rex will come back to life able to attack things again.


 * If Rex is told to wait for you at the Lucky 38 he may not be found there when you return but he might be found back with the king and when approached will start running back to the Lucky 38


 * Rex might sometimes not follow when fast traveling. He will be waiting on the spot you traveled from. He will still be in your party and will follow you if you select "follow" through the companion wheel. Other times he will stay put after a fast travel. Selecting "stay" then "follow" will make him follow you again.--(Confirmed 360)


 * Rex will sometimes wait without being told to, this can be fixed by telling him to wait, then tell him follow you again.


 * If you talk to Rex as soon as you get him for Nothin' But a Hound Dog, and the Perk for having him with you pops up, you will enter chat with him, but will have no options to talk. (Screen zooms in, he turns towards you, and no chat options appear.)


 * If you separate from Rex and tell him to go to the King, the pop-up message will tell that Veronica went to lucky 38 (In the French PAL version at least)


 * Rex may sometimes attack and kill an NPC for no apparent reason (Whether it is a bug or something to do with the characters disdain for hats as a cause is unknown). This makes it important to have a few backup saves when using Rex as a companion. One known possible unprovoked attack location is the Ultra-Luxe hotel, where Rex, strangely, has been seen attacking and killing a hat-less female NPC in the lobby, while hat-wearing Heck flees the scene. Another thing, if he's left with the NCR at Hoover Dam, he might start attacking them. He may also start attacking the red suits in the tops(and Tommy Torini), in which the red suits will win.


 * If taking a very steep route down a mountain, Rex will sometimes run a much longer route and may get stuck in rocks; to resolve this you can walk around the rock until Rex frees himself, or load a previous save.


 * While doing the quest You Can Depend on Me (Or just trying to sneak into the Gun Runners), Rex may glitch while in combat with the guards and end up in the Vendortron's kiosk. There is no physical way into the kiosk and Rex can still be spoken too. The only way to fix this problem is to fast travel to another loation, in which Rex will appear beside you.


 * [hardcore mode only] When trading equipment with Rex, he can be over burdened with ammo if the ammo is in multiple amounts. First take the large amount of ammo out, then place as much ammo as you want into his inventory. Said ammo will not be lost, but when the ammo is taken out you must repeat the glitch to put any ammo back into his inventory. (Other Platforms need confirmation)


 * While vilified by the Legion, if Rex simply kills Lupa while you are disguised and have her brain transplanted by Calamity, the epilogue may state that Rex never got a replacement brain even though the quest is completed, rather than the correct ending.

when sent to the lucky 38 other companions attack him for no reason they will not attack if he is following you