Thank the gods for the Banshee Queen!
In life, Sylvanas Windrunner had been a high elf and the ranger-general of Silvermoon, capital of the kingdom of Quel’Thalas in northern Lordaeron. Defeated by the Lich King’s champion, she had been raised into undeath. But somehow, she found a way to break the Lich King’s hold on her mind and will. Tearing herself away from the Scourge, she sought out others among them whose souls were merely buried—not obliterated.
She found Reigol Valdread. Her power freed his mind, his will, his soul, but could not restore his body or his life. He became Forsaken, swearing fealty to the Banshee Queen. He fought at Windrunner’s side against the Scourge and those who did or would control them. He marched against them throughout the north.
But at some point, it became clear that the march would never end.
He grew bored with killing the dead. He knelt before Sylvanas and asked her to release him from his vow. She was—begrudgingly—willing. Though she demanded loyalty, she would not hold her agents in thrall. She understood the call of freedom better than most. But she warned him that few in Azeroth would accept him as the Forsaken had. Even the most open-minded, who understood that his was not a condition he had chosen for himself, would ne’er be able to stay in the same room beside him for long due to the stench of death he carried with him everywhere he went.
Nevertheless, Baron Valdread took his leave of the Banshee Queen and the Plaguelands.
Excerpt From The Traveler: The Spiral Path (World of Warcraft) by Greg Weisman.
As a side note, the Traveler books are fantastic if you can overlook how kid-friendly they are.