What are your opinions and feelings on warriors that don’t exist in the physical world, but instead in a character’s mind and dreams?

What would you call this type of warrior, and the characters whose minds they occupy or reside in?

Would their appearance and/or attitude symbolize and/or represent conscious and unconscious feelings and opinions of the character whose mind they occupy?

Would they be beings from a different plane of existence (e.g., spiritual), or would they be born entirely from a character’s mind?

If the latter, would they also be a mental immune/defense system? Have their own personalities? Possess free thinking, self-awareness and free will to a certain extent? Be aware that they exist only in someone’s mind?

Would they just inform/update others of current conditions, or would they also interact similarly to humans IRL?

Would their combat-related skills and traits be identical to the those of who they “reside” with? Different? The complete opposite?

Would they possibly be able to be summoned in the real world? If so, with what limitations, if any?

I am currently working on incorporating this type of warrior in a story, and haven’t been able to think of a name/term for the type.

If they reside in the dreams of another I would imagine their personality would be either a reflection of the mind they reside in, or a subconscious part of that mind. Their powers would probably resemble what the person who thinks of them attributes to them. IE a warrior that represents anger would use fire as a weapon. However being part/ existing in a dream world they could be anything they wanted to be if they have a mind of their own.
Thats just my take on them anyway