Who Killed Strelitzia 2020?

In the latest Kingdom Hearts χ update, it is revealed that Darkness killed Strelitzia while possessing the body of Ventus. As Darkness steps into the light, it assumes the form of Master Ava, showing that Ventus believed he was merely having a meeting with the creator of the Dandelions.

What union is Strelitzia in?

Strelitzia was a Keyblade wielder who appears in Kingdom Hearts Union χ. She was a member of the Dandelions and was chosen by the Master of Masters to lead a Union after the First Keyblade War.

Was Ava the traitor?

Given this, Ava is 5/5 for being the traitor, while this would technically put Luxu at 2/5. So going by what Gula tells us about the Traitor and The Lost Page, it's undeniably Ava.