Talius

Talius is a mutant who resides in the basement of the library of the Followers of the Apocalypse.

Talius was a Vault Dweller, sent out to find the Water Chip. Together with Ed, this means there are two confirmed Vault Dwellers from Vault 13 who went out before the PC of Fallout. He has had a rather nasty encounter with the mutants from Necropolis and became a ghoul-like mutant similar to Harold as a result of FEV exposure.

As you can imagine he's a bit upset about that, so he'll help the PC along by giving him a flamer if he promises to battle the mutants (in Necropolis) or has killed them already or Mentats if the PC is extremely stupid.

Talius is also a part of the Find Children spy in the Followers, a quest he'll give you if you accuse him of being the spy. This quest is broken and can not be finished

It is not known what happened to Talius, but it can be assumed he died when the FotA were massacred by the remnants of the Master's Army