If you do not talk to your quest leader by a certain turn count, a peaceful same-role player monster NPC named Chad, Stacey, Kevin, or Jennifer should appear on the quest start level, with the implication that they already did the quest.

• The NPC is equipped with ascension-level gear which includes your role’s quest artifact and a wand of death missing at least one charge.
• When you chat to the NPC, their lines consist of humble-brags and passive aggressive insults about your gear.
• The quest leader’s lines are replaced with glowing praise for the exploits of the NPC.
• They do not have the Bell of Opening; the nemesis still has it. The implication is that the interloper made a backroom deal with the nemesis to make your own game harder.
• The quest leader will allow you to enter the quest to get the Bell, since they are aware it is needed for getting the Amulet of Yendor, but the levels of the quest will not generate any floor objects, while still having all or most of their monsters - the implication being the NPC looted everything already.
• There should be a TDTTOE case for when the hero is already named Chad or Stacey.