"I am on borrowed time."
What if Varus (Human) made a pact with the Varus (Darkin)?
Instead of the whole 3-way fusion non sense that becomes basically Kayns lore.
Varus (human) loses everything in a raid (to Noxus or whoever) so then Varus (human) makes a pact with the corruption (Varus the Darkin) he was meant to protect from getting lose to seek his revenge?
"I am on borrowed time."
Instead of the copy/pasta of Kayns lore, where he and Rhaast fight for one body, Varus signs his body over to the Darkin til after his vengeance is over. Darkin love murder, violence and vengeance as well as Darkin are immortal, time is no concern to them.
"Ha, I can wait a few years at worst and I will gain my freedom and a new host with out a struggle. As well as watch some good 'ol carnage. Win. Win."
"Fear a man with nothing to lose."
As Varus looks down at his locket of his gay lover. He clasps it in his hand as he stares down a Noxus encampment. Outnumbered and full of determination. No fucks left to give.