Persona

I am though, and though a'rth I A Persona's greeting to their partner prior to summoning

A persona is a tamed shadow that protects its human host from shadows and other threats in the Fog World in the series Persona 4: The Animation.

Anatomy and abilities
Like Shadows Personas come from the Fog World; a parallel Universe formed by the collective subconscious and negative feelings of humanity. A Persona will start life as a Shadow that looks like the human it was spawned from. The only difference is the double possess yellow cat like eyes and a distorted voice.

Very rarely a Persona will be spawned in its Persona state; this will only occur if the human it is connected to has nothing to hide.

When they have found their human the Shadow will confront the human with their darkest, hidden secrets attempting to get the person to accept them. More often than not the human rejects the entity; horrified and ashamed by its acusations. This will cause the Persona to mutate into a monstrous creature unique to the individual that will then attempt to attack and kill their human counterpart. If the creature is injured sufficiently enough it will revert into a humanoid form.

If the human accepts the entity it will transform into its Persona state; its appearance unique to its owner and possessing combat abilities that match their personality. It will then dissolve into a blue energy that will enter the human; becoming a part of them. The joining process is a draining experience; many humans are left fatigued and slightly ill for a day or two after the event.