Kain Darkwind's Savage Tide
Jerard Mathias was a childhood friend of Heinrick Gilantheril, who left Home together with Heinrick in search of adventure but was slain in the Vanderboren family vault in Sasserine by the vault’s guardians during There is No Honor.
Jerard later seemed to return to life by the agency of some unknown power during The Sea Wyvern’s Wake, but what had appeared to be Jerard was later revealed to be actually a Hollow, a soulless husk serving as a vessel for a demonic master. Jerard’s soul was trapped in the Abyss, a prisoner of the lilitu Crimson.
Upon his discovery that his entire identity was a lie, Jerard took the name Tainthorn. He slowly began manifesting demonic features, but his actions were if anything, more heroic than ever. During the events of Here there be Monsters, he rescued a group of survivors and led them inland, where they rejoined Heinrick and Kat’s group after Olangru’s savage attack.
Tainthorn went into the shrine of Demogorgon with the pair, alongside Heldin Rockhammer. In the final battle with the bar-lgura, he aided them in slaying the demonic master of Fogmire. When the Lemorian Golem awoke, however, Tainthorn was forced to sacrifice himself in order to save the others. His death bought his companions enough time to bring down the deadly construct.