Captain Braindeath is a pirate captain who is in charge of running the secret brewery on Braindeath Island that produces Braindeath 'rum', yet the island has been invaded by zombie pirates and he cannot continue brewing with them in the way.
In order to overcome this, he sends Pirate Pete to the coast of Morytania, to the north of Port Phasmatys, so he can find an adventurer that can get rid of the zombie pirates, which Pete manages to do (by means of deceiving the player with a story of a demon, a half-brother and some inheritance he can't claim). After meeting with the player and explaining the situation, he has the player collect the ingredients for his 'rum' and exorcise the control panel for the fermenting vat, which has been possessed, so that they can distract the zombie pirates while he and the brewers escape. After the player manages to fetch a bucket of 'rum' to Captain Donnie, the zombie pirates' captain, he accidentally slips that he works for a pirate named Rabid Jack, whose name clearly shocks Braindeath by its sole mention. Pretending to have never heard of him, he rewards the player and manages to keep the brewery working by keeping the zombie pirates drunk with his 'rum'.
During the Rocking Out quest, he requests the player to convince the Bartender in The Rusty Anchor inn in Port Sarim to stock up his 'rum'. He will provide players a set of 5 disguises to wear for this mission. These include:
If players are successful, he will give them his mark so that Young Ralph will tell them about the tale of Rabid Jack.
During A Clockwork Syringe, the player goes on behalf of Bill Teach to ask Captain Braindeath for a Twiblick night special in order to interrogate a zombie pirate that tried to murder the player in his own house. However, Braindeath is more concerned about the disappearance of three of his brewers who went to investigate a mysterious entrance which had recently been unearthed in a rockfall to the north of the island. The player agrees to investigate the entrance and find the brewers in exchange for the Twiblick night special. Later, the player reports that zombie pirate surgeons have been injecting the dungeon's crabs with his 'rum', which made them go berserk and kill the brewers who went to investigate. Blaming this on Captain Donnie (who he had been supplying with his 'rum'), he promises not to give him any more 'rum' and gives the player the Twiblick night special, not before making him/her swear an Oath that stipulates that if he/she ever tells anybody about the Oath or the contents of the Twiblick night special, he will "smash their face with an anchor", pointing out that "he's definitely not kidding".
During Rum Deal, he claims to not actually be a pirate, but rather an alchemist who suffered brain damage when he first created his trademark 'rum' which caused him to speak like a pirate. The player doesn't believe this, and his presence at the Battle of the Archipelago casts further doubt on his claim.