Rex (Fallout: New Vegas)

Rex is a cyberdog in Freeside under the ownership of the King. In 2281, he is suffering from neural degeneration as a result of his old brain.

Background
Part German Shepherd, Rex is a "cyberhound Mk III law enforcement officer support model" that has been around since pre-war times. He was born as a regular dog in 2072 and served in the Denver City Police Department. Sometime before the war, he was cybernetically enhanced and turned into a cyberdog - serial no. B955883, although the circumstances of his cybernetic alterations remain unknown, and served after in the K-9 unit. He survived the destruction of Denver and the harsh wastelands, eventually becoming Caesar's companion, but was lost in a battle. He later reached Freeside, where he came under the ownership of the King, who loves him dearly. Rex does not like rats, or hats, according to the King. The King says his dislike of hats may come from the fact that hat rhymes with rat.

Quests

 * Nothin' But a Hound Dog: The player has to find a replacement brain for Rex by taking him to Dr Henry in Jacobstown.
 * You'll Know It When It Happens: Rex can sniff out the disguised assassin for the player without having to search around for him.

Other interactions

 * If the player has the Wild Wasteland trait and talks to Rex, the Courier can ask if Jimmy has fallen down a well. This is random and does not always happen. This adds the location Jimmy's Well to your map. Down in the well you will be confronted by a mole rat, and there will be a skeleton. Next to him is the Abilene Kid LE BB Gun, 2 tins of BB's, a super stimpak and a rawhide cowboy hat. This is a reference to the television show Lassie, as well as to the quest with Laddie in Fallout 2.
 * This happens while you are in Jacobstown when you talk to Rex.
 * It will also happen if you upgrade Rex and talk to him at the Mojave Drive-In (PS3 with Dead Money, Honest Hearts and installed).

Endings

 * If he never receives a replacement brain, Rex finally succumbs to old age, abruptly shutting down forever one quiet morning. After two centuries of life and decades of service to humanity, Rex collapses and dies.
 * If revitalized by Violetta's brain, Rex eventually learns to balance the memories of his old life with Violetta's experiences among the brutal Fiends. His mind has difficulty adjusting, but Rex eventually finds peace with his new, more vicious self.
 * If he receives a transplant of Lupa's brain, Rex gains all of the donor's experiences traveling with the Legion. These meld well with his own memories of the Legion, and his new mind quickly adjusts to the myriad of memories.
 * If Rey's brain is transplanted into Rex's cybernetic body, it takes Rex some time to adjust to the old scrap yard dog's memories. Eventually, Rex's mind settles peacefully, melding his own memories with that of long travels with Old Lady Gibson.
 * At the end of Old World Blues, if Roxie has been created and is still alive by the end, Rex, regardless of his status, is found by her and they go on to build puppies.

Appearances
Rex appears only in Fallout: New Vegas.

Bugs

 * After returning from The Big Empty, when trying to talk to Rex, he will bark and will not be able to enter dialogue. To fix this, Crouch and try to talk to/pickpocket Rex and you should enter dialogue.
 * When Rex is acquired, and if you tell him to wait in the Lucky 38 presidential suite, sometimes he will not be there. If this happens, go to the King's School of Impersonation in Freeside where he can possibly be found in the hallways there at which point he runs back to the Lucky 38 instead of fast traveling there.
 * Sometimes simply entering and exiting the King's School of Impersonation will cause Rex to appear and run to the Lucky 38 when you exit.
 * Sometimes, Rex will disappear from the game if you send him to the Lucky 38. Remarks about him will still come from NPC's and his perk will still be with you, however; you won't be able to fire him meaning you will only have one human follower and will not be able to have ED-E tag along with you (This is because ED-E is a robot and you can only have one human and one non-human following you at the same time). UPDATE: Can now be fixed via the Companion dismissal terminal.
 * Rex may die randomly while in the Remnants bunker
 * Rex loses health when near the Remnants bunker. Fast travel to some other place if you see his health drop.
 * 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. Don't travel from The King to Henry and back, Rex still won't be there! When you realize he's gone, load the last saved game, go to Jacobstown and then visit The King.
 * During combat, Rex might chaotically run around from-and-to foes while not attacking anyone. He may also in fact not attack at all when you have him.
 * Rex will sometimes stop moving as if he has been told to wait. You will need to keep checking to see if he is still with you. This can usually be fixed by telling him to wait, then tell him follow you again, fast traveling or going through a door that requires a transition. However these fixes are per incident and he will randomly do it again.
 * 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 to. The only way to fix this problem is to fast travel to another location, in which Rex will appear beside you in patched versions of the game.
 * 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 you are knocked out in Dead Money when you escape, you might not be able to find Rex anywhere. He might be found in the lobby of The King's School of Impersonation.
 * If Rex and another person (i.e. the player or another companion) attack the same enemy at the same time and the game goes into slow motion kill-cam, the game may freeze. Turning kill-cam off may solve this problem.
 * Rex may occasionally start unprovoked attacks, even with Passive mode on. Telling Rex to wait a distance from the person can fix this.
 * If you tell Rex to wait outside when visiting Caesar in the quest Render Unto Caesar and you confirm that you want to battle Benny, the game will automatically send you to the ring, and when you win, Rex will be nowhere to be found. He isn't with The King or at any casinos. If you were already at the point in Nothin' But a Hound Dog where you are looking for a new brain, you can still gain a brain as the AI will think you still have Rex, but when you go back to Doctor Henry, he will say he can't perform the surgery without Rex. To fix this in the PC version open the console and type  - Rex is located next to the arena along the outer fence.
 * When acquiring Rex from The King in his room, very top floor of The King's School of Impersonation, he will sometimes drop through the floor and wind up at the bottom level. Just wait a few minutes and you will find him running towards you.
 * If you enter and exit Gomorrah while Rex is following with you and has weapons in his inventory, the weapons may disappear completely even after leaving the casino.

Gallery
ru:Рекс (Fallout: New Vegas)