Solipsism

Solipsism is the philosophical idea that only one's mind is sure to exist. As an epistemological position, solipsism holds that knowledge of anything outside one's own mind is unsure; the external world and other minds cannot be known and might not exist outside the mind. Solipsism as a metaphysics holds that there's nothing outside the one's mind.

Personality
Doesn't know how to comprehend anything that exists outside of his own mind.

Friends
Solipsism - The only and most precious thing in the world.

Frenemies

 * [Egoism] - Serving myself is a good idea.
 * Nihilism - The denial of all established morality, authority, social convention - and then the return to the individual centre.
 * Idealism - It is my OWN mind that determined my existence.

Wikipedia

 * Solipsism