Revisiting Richard Hays' The Moral Vision of the New Testament in preparation for putting together a long study of Mark's gospel, I came across this gem:

Nowhere...does the Markan Jesus promulgate love as a distinctive mark of discipleship. The disciples are summoned to follow, and the single fundamental norm is laid down in the narrative of Jesus' own death on the cross. Unlike Paul and John, Mark nowhere explicitly interprets Jesus' death as an act of "love." The way of the cross is simply the way of obedience to the will of God, and discipleship requires following that way regardless of cost or consequences. (84-85)

Nothing against love, of course, especially in the Christian life. Just interesting that it can't be used as an organizing principle for understanding who Christ is or what the nature of discipleship is according to the Gospel of Mark. Instead, obedience to death, a Pauline theme as well in places like Philippians 2.