Desther Indelayne is introduced as the leader of the Helmites in Neverwinter during the prelude to the Original campaign. He argues with Fenthick Moss about the correct way Lady Aribeth de Tylmarande should deal with the Wailing Death. Desther has Helmite priests throughout the city of Neverwinter that give out blessings.
Throughout the prelude and first chapter of the original campaign, Desther is often distrusting of the hero, proclaims that Aribeth acted foolishly, and constantly argues with Fenthick. He also discourages inquiry into assassination attempts made on the hero after the hero begins recovering the reagents needed to cure the wailing death.
At the end of the first chapter, after the cure for the wailing death is created, Desther steals it and sends false Helmites to slay the temple inhabitants. He is later encountered on the upper level of Helm's Hold, which is now filled with demons, zombies, and false Helmites. By this time, it has been revealed that he and his false Helmites spread the wailing death in service to a cult. However, the cult no longer needed him, and so removed his support. In anger and desperation, Desther raised the undead encountered in Helm's Hold.
It is shown that Desther has tremendous ability in convincing people he is good, in deceiving many without telling a straight lie, and in keeping up a ruse indefinitely. It is through these skilful means that Fenthick feels internal guilt in his association with Desther and is convinced that he ought to take responsibility for the plague.
Desther also has internal issues in his allegiance to the cult. Through assorted conversations, including Morag's disgused projection outside the Helmite temple prophesying Desther's doom and Desther's after combat dialogue, it is revealed that Desther has been charged by Morag with not spreading the plague through Helmite "blessings" at anywhere near the expected rate, taking time and means to safeguard and protect his followers rather than get the job done, and showing lack of unswerving allegiance to the cult by considering his relationship to be more mercenary. It is thus that Desther's allignment happens to be true neutral.
Desther gives up fighting fairly early in the combat, seeing that the situation for him is meaningless. Nevertheless, he still withholds critical information concerning the cult. After his defeat, he is executed by being burned at the stake.