He offers help to the Dragonborn in order to commune with the Daedric Prince Peryite, by giving him a list of ingredients and materials needed for a summoning ritual in the quest, The Only Cure. Despite being a worshipper of Peryite, Kesh does not seem to be one of the Afflicted. He claims to possess adequate skill in Alchemy. Kesh's apparel consists of miner's clothes, boots, and an Alik'r hood.
Unlike most other NPCs bound to a quest, Kesh can be killed, seemingly preventing the Dragonborn from starting The Only Cure.
If Kesh is killed, the quest can still be activated by travelling to the large Dwemer pot at the Shrine to Peryite with the ingredients the quest requires (see walkthrough). If the Dragonborn accidentally kills him, the quest will not be failed. The Dragonborn can still complete the quest and obtain the Spellbreaker and Oblivion Walker achievement.