Leonid was a noble hero until he was killed and later resurrected by the Lich King as a mindless undead. He was present at Stratholme when Ras Frostwhisper gained his immortality. He was freed by the Banshee Queen, and became one of the Forsaken. Eventually coming to mistrust the Forsaken agenda, he left them, and is now an active member of the Argent Dawn. Before his departure he befriended the Forsaken priest Trevor who holds Leonid in high esteem and aspires to follow after him.
Leonid considers his undead condition as a mere illness which requires treatment. It is also a source of poetic justice for the Argent Dawn and himself: what could be more fitting to smite the abominations of the Scourge than one of the redeemed undead?
The Argent Dawn give him special recognition because of the sacrifices he has made, but the accolades mean nothing to him.
Leonid starts the following quests:
Wrath of the Lich King
This section concerns content exclusive to Wrath of the Lich King.
Barthalomew appears leading the Argent Dawn at the Battle for Light's Hope Chapel before the arrival of during  .
Warlords of Draenor
Leonid can appear in the player's Garrison tavern, requesting a Soulweave Vessel from Auchindoun.