Mister Crowley is as bitter a ghoul as you could find. He was transformed 10 years ago due to an extreme exposure of radiation that should have killed him. He once lived at Rivet City, but the bias and hatred he experienced there forced him to move on. Crowley discovered Underworld and has taken up permanent residence, but remains resentful of the harsh treatment he received from humans. He presents the Lone Wanderer with a complex revenge plan that he wants you to carry out. Mister Crowley spends most of his time in the Ninth Circle, drinking heavily.
If the Lone Wanderer retrieves the keys detailed in his quest, he/she can go to Fort Constantine and take the T-51b Power-Armor. Mister Crowley won't be too happy with this and only respond with, "You stole what was rightfully mine. Get lost.", without an option to give the suit to him. He will say the same thing if the Lone Wanderer pickpockets the keys from him after giving them to him.
If the Lone Wanderer hands Crowley the keys and later travels to the Fort Constantine's Bomb Storage section he will be inside wearing the armor and thank the Lone Wanderer for the keys.
If the Lone Wanderer kills Crowley at any time, he/she will no longer be able to collect caps for this quest. The Underworld will turn hostile for 72 in-game hours if the Lone Wanderer is detected in this act.
Crowley can die on the way to retrieve the armor, making him hard to find and the armor unobtainable.
Crowley has green hair, which is rarely seen on other characters.
After obtaining the armor, Crowley can appear randomly at places which the player has fast-travelled to or waited at.
Crowley was supposed to have a very high DR perk to make sure he will reach Fort Constantine, but it was removed from the game. Instead, Crowley benefits of a micro regen perk so if he is not killed outright during a fight he will slowly recover health and get cured of any crippled limb. This perk is granted only during the travel to Fort Constantine.
Interestingly, if the Lone Wanderer tails Crowley to the fort, he will be attacked by super mutants despite several sources saying super mutants don't bother ghouls.
Mr. Crowley is possibly named after Aleister Crowley, a famous British writer and occultist. (Aleister Crowley's first name is often misspelled Alistair or Allistair, as in Allistair Tenpenny, the arch-nemesis of Underworld's Mr. Crowley.)
pcxbox360 Occasionally, Crowley will go into a bout of slow motion sprinting, running at nearly half speed but with full striding animation. He will resume normal movement upon his next combat encounter. [verified]
pcps3xbox360 Crowley may deliver the "You stole what was rightfully mine!" line if the Lone Wanderer acquires the winterized T-51b power armor helmet from the Anchorage simulation. [verified]
pc With Broken Steel installed: After getting the T-51b power armor and T-51b power helmet from Fort Constantine by unlocking all the doors, then finishing the You Gotta Shoot 'Em in the Head quest by giving Crowley the keys, and fast traveling back to snatch the armor before Crowley finds out, Crowley has been encountered still friendly in the Presidential Metro, just inside the doors from M.A.R.Go.T., during the Who Dares Wins quest. [verified]
xbox360 Occasionally, Mr. Crowley will not appear in the Underworld. [verified]
ps3 If the Lone Wanderer gives Mr. Crowley the keys, pickpockets the keys back and goes to Fort Constantine to get both his reward and the T-51b Power-Armor without having to kill him, he will disappear from the game. [verified]
pc If the Lone Wanderer hands Crowley the keys and manages to obtain "his" power armor from Fort Constantine without these keys, he might show up later and attempt to kill him/her. [verified]