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, and it's unknown why, although the King says it might be because "hat" rhymes with "rat".

Background
Rex is a cybernetic dog that has been around since pre-War times. He was used by the Denver Police Department. Since then, he's been the loyal pet of The King of The Kings in Freeside. Capable of sniffing out loot and taking a large amount of punishment. He can become your companion during the quest Nothin' But a Hound Dog. After the quest he will become permanent. When asked to get a new brain for Rex, if you ask the hound master in The Fort, he will ask the player where he found Rex as Caesar had one just like him, but he was lost in battle, and presumed dead. The three Brains that can be used during the quest Nothin' But a Hound Dog are: Lupa's Brain from The Fort, which brain increases Rex's health from 450 to 550, Rey's brain, which increases Rex's Attack, an NCR Guard dog brain, which has no effect, and the brain from Violet's guard dog Violetta (which can be acquired during the quest Three-Card Bounty), which increases Rex's speed.

Appearances
Rex appears in Fallout: New Vegas.

Bugs

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


 * After replacing Rex's brain with Lupa's, his health is reset to 100/0 (440/440 is default). Rex gets knocked out after one hit.


 * 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.


 * Currently, Rex has a bugged dialogue-script at the end of "Nothin' but a Hound Dog". After his brain is transplanted, Rex will come forward to you and the game will freeze. (Needs confirmation/details? Seems like transplants are working)


 * 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. This obviously made Lupa's brain's "Blood of the Legion" perk effectively useless.


 * 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 be 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