Jeremiah will ignore the player if they are wearing robes, otherwise, he will either throw them out of the Cathedral or have to be killed.

Otherwise, they can either blow up the door or wait for Jeremiah to open it.

To open the secret door to the lower right, the player can use Traps or Lockpick on the lowermost bookcase to reveal a secret lever, then use it as normal.

With 100% Lockpick or better, it's also possible to open the door into the basement.

Stealthy characters can use the robes and try to assassinate Morpheus to loot the badge from his corpse.

This instantly transports them to the Master's chambers for a diplomatic confrontation (see below). They can talk to Morpheus, reveal their identity as the Vault Dweller, then agree to meet the Master.

Diplomats can wear robes or carry the red COC badge and as long as they have no party members or the invaders on their tail, the nightkin won't attack.

They wear metal armor, and are equipped with melee weapons: A sledgehammer, Ripper, and two spears and will follow the player everywhere in the Cathedral. To this end, the player can convince Nicole to send some backup in the form of Follower invaders, who provide useful cannon fodder and can be kept alive by juicing them up with drugs ( Buffout for Strength and durability, Psycho for the damage resistance). The nightkin are a challenge, but the real prize is Morpheus and his COC badge that unlocks the door into the basement.

The combat solution is to kill everyone, at least in the Cathedral's tower.

Accessing the Vault in order to confront the Master requires first getting into the basement.

In order to destroy the Master, the player first needs to reach the Cathedral, located south of the Boneyard.

The Vault Dweller is ordered to hunt him down and destroy him. The safety of Vault 13 can only be ensured by the total destruction of the mutants, including the Master.

Fallout 1 super mutant invasion