Krishna is that within you that already knows
Krishna is that in Arjun that already knows. In a physical setting Krishna appears like a man outside of Arjun. Actually speaking, Krishna and Arjun are not separate.
Krishna is the one that Arjun goes to, when he wants to validate all that which he already knows. Krishna is the Heart of Arjun. That Heart is also known by the names — Lover, Friend, Guru.