"And you are my friends if you do what I command you. I do not call you servants any longer, because servants do not know what their master is doing. Instead, I call you friends, because I have told you everything I have heard from my Father."

(John 15.14-15 GNB)

Jesus' friend, in this definition, is someone who hears from the Father through Jesus and do them. Someone who knows what the Father is doing and do what he commands. "Do what I command you" seems at odds with my daily understanding of friends. But on second look, I can see some similarities.

A friend is someone whose interests are aligned with my interests and we support each other to achieve these interests.

Jesus' interests revolve around doing what the Father commands and he wants me to do the same. When my interests align with his, I am his friend.

See: As a friend