Jesus says in John 18:36,
My kingdom is not of this world. If it were, my servants would fight
to prevent my arrest by the Jewish leaders. But now my kingdom is from
But there's a problem with that statement. Peter has been fighting. And he attacked Malchus, a man who's name means king or kingdom.
Only John of the four gospel writers makes the connection between the one who drew the sword and Peter. In Mark, as well Matthew and Luke, cutting off the ear is symbolic of a lack of hearing and understanding (Mark 7:35, 8:18). In John it certainly has this connotation as John proceeds to interweave Jesus' bold confession with Peter's three denials.
Peter's attack is a symbolic depiction of Peter's fundamental misunderstanding of Jesus' kingship and kingdom.
This interpretation does not rule out Malchus from being a real historic human being that John knew. It only explains why he would have added this detail for his audience.