Old World Blues ( quest ) Old World Blues is the final of the " " " Old World Blues " . After completing this quest , the Make up Your Mind and Outsmarted will be earned . Detailed walkthrough . The Courier can begin this quest by speaking to Dr . Klein , where the good doctor will tell them that it ' s time to go to the Forbidden Zone and get their brain back . He also asks the Courier to deal with Dr . Mobius . Optional Speech checks are available : The player character should begin by traveling to the Forbidden Zone , once there , the Courier will encounter several robo - scorpion s surrounding the entrance . After dealing with them and entering the zone itself , Dr . Mobius will release his most powerful creation , the X - 42 giant robo - scorpion . After defeating it , the Courier must confront Dr . Mobius . To do so , take the stairs to the left of the entrance and enter the door on the right . There they will meet Dr . Mobius , who is not hostile . Here there are two choices : reason with him or kill him . Option 1 : Reason with Dr . Mobius If reasoning with Dr . Mobius is chosen , he will direct the Courier to their brain where they must convince it to return . Optional speech checks are available with him : Option 2 : Fight Mobius If the Courier chooses to fight Mobius , Dr . Mobius will release 5 MK4B robo - scorpions . They will need to defeat Mobius and the robo - scorpions to continue . 1066 XP will be given for defeating Mobius . Once Dr . Mobius is dealt with , the Courier must then speak to their brain , and convince it to join them again . Having high Medicine , Speech or Science will give them a significant advantage and make the dialogue much easier . The use of the unique dialogue provided by Confirmed Bachelor / Cherchez La Femme / Black Widow will result in a somewhat humorous , if mortified response from the brain that does not help much . Talking to the brain and convincing it to help in the final quest stage will grant the Make up Your Mind achievement / trophy . Optional speech checks : If Mobius is alive After acquiring the brain , the Courier needs to speak to Dr . Mobius again . He ' ll tell them more about what the Think Tank is all about and suggests dealing with them , instead of him . The choice is up to the Courier . If Mobius is dead Walk up to the Courier ' s brain and speak with it , thus re - acquiring it . After making the choice , the Courier needs to go to the the Think Tank . Then , the quest will end to a cut - scene . After that , The Courier will have their Brains installed . There they have the option of using the Sink ' s Auto - Doc to retrieve their original heart and spine . Option : Reason with the Think Tank For those wishing to reason , the speech checks are : Option : Fight with the Think Tank The Courier must destroy all five members of the Think Tank . After completing the quest , and watching the ending slide show , the Courier is given the Big Mountain Transportalponder ! . This will allow one to return to the Big MT via The Sink balcony at any time , or from Big MT to the Mojave Drive - in , although using it is limited to locations within the Mojave Wasteland , and cannot be used in areas such as the Strip or while in combat . Furthermore , upon completion , all active personalities in The Sink will cheer for the Courier ' s victory , with a particularly drawn - out and rambling congratulations from Blind Diode Jefferson . After the slide show ends , ( and the Courier convinced the brain to come back ) , the brain will either be located in the far left room , ( where the heart and spine have been stored ) or in the Courier ' s inventory . They will then be able to re - transplant and de - transplant their brain later at any time or leave it in the storage facility . Doing so will change brain , heart , and spine - related perks .