William Allerton was a friend of Thassarian.
World of Warcraft: Death Knight EditThis section concerns content exclusive to Warcraft-related manga (or manhwa).
In World of Warcraft: Death Knight, it is revealed that he once had a crush on Leryssa, the sister of Thassarian. He and Thassarian were assigned to the expedition with Prince Arthas Menethil to hunt down Mal'Ganis. The expedition was a success, but Arthas and Falric went in the wastes and Thassarian went after them.
After learning what Arthas had done, William was able to survive his wrath and made his return trip to Lordaeron, but when he returned, he witnessed a Death Knight killing Vivian and threw an amulet that she gave Thassarian before he left to travel to Northrend. William believed that this was the death knight who killed his friend Thassarian, but he did not realize that the Death Knight was actually his best friend. Years later, William volunteered to join the Valiance Expedition that settled in Northrend and would soon learn that his friend Thassarian had in fact survived.