Lurald is one of Leonof's puppets—basically a marionette controlled by the Puppet Master himself. His actual identity is pretty murky, but most fans figure he was probably human once before Leonof killed him and converted him into a puppet through whatever twisted craft Leonof uses.
Leonof put Lurald to work leading a small terrorist cell, using him as a way to push Vash and test how far he'd go. In the anime adaptation, Lurald gets bumped up to Leonof's primary puppet, and there are apparently multiple copies of him in circulation, which adds another layer of creepiness to the whole setup.
Content compiled by AnimeList.moe from publicly available sources.
