The Story of Viego
Viego was once a king — the ruler of a pre-Runeterra kingdom so ancient that its name is no longer remembered. By all accounts he was not a particularly good king: self-absorbed, negligent of his responsibilities, focused on his own desires to the exclusion of anything that required sustained effort or care for others. The one exception was Isolde, his queen, whom he loved with an obsessive, all-consuming devotion that left no room for anything else.
When Isolde was poisoned by an assassin's blade, Viego refused to accept her death. He had heard of the Blessed Isles — a place of ancient healing magic — and he went there with Isolde's body and the certainty that love of sufficient intensity could undo any harm. What happened instead was the Ruination: the dark magic he invoked to try to restore Isolde tore through the Blessed Isles like a wound, transforming paradise into the Shadow Isles and killing or corrupting everything on them.
The Ruined King now wanders the world he destroyed, still looking for Isolde, still believing that finding enough of her soul — scattered through the people touched by the Ruination — will restore her. He possesses the bodies of the living, consuming them to feel something like closeness to her. He is one of the most dangerous beings alive, and everything he's done and everything he is can be traced to a love that was never mature enough to understand that love cannot undo loss.