Friends are always the best part of our lives. I would hazard a guess that every culture has a word for friendship. Friends come in many types from passing acquaintance to deep family-like bonds. They also come in at various levels spiritually. We may not always agree theologically but the bond of brother and sisterhood in God is what truly makes us friends, as Jesus called the disciples at the Last Supper.
Quodvultdeus was one such friend to Augustine. While we easily recognize Augustine's name, his probably escapes us, even though Augustine dedicated several works to him.
Their friendship may have come to an end when Carthage was invaded by Arian Vandals and Quodvultdeus was unceremoniously exiled to Naples never to visit or see his friend again, but he continued to oppose the heresies of Arius and Pelagius.
We are molded by friendship, especially if we are blessed in the ministry of marriage. The effect that these two men had on each other is reflected in the effect they had on many, many others.
As an aside, just looking at his name, it can break apart into "Quod vult deus" which roughly is "What will God?"
A tiny child is born, who is a great king. Wise men are led to him from afar. They come to adore one who lies in a manger and yet reigns in heaven and on earth. When they tell of one who is born a king, Herod is disturbed. To save his kingdom he resolves to kill him, though if he would have faith in the child, he himself would reign in peace in this life and for ever in the life to come. Why are you afraid, Herod, when you hear of the birth of a king? He does not come to drive you out, but to conquer the devil. But because you do not understand this you are disturbed and in a rage. To destroy one child whom you seek, you show your cruelty in the death of so many children. You are not restrained by the love of weeping mothers and fathers mourning the deaths of their sons, nor by the cries and sobs of the children. You destroy those who are tiny in body because fear is destroying your heart. You imagine that if you accomplish your desire you can prolong you own life, though you are seeking to kill Life himself. The children die for Christ, though they do not know it. The parents mourn for the death of martyrs. The Christ child makes of those as yet unable to speak fit witnesses to himself. But you, Herod, do not know this and are disturbed and furious. While you vent your fury against the child, you are already paying him homage, and do not know it. To what merits of their own do the children owe this kind of victory? They cannot speak, yet they bear witness to Christ. They cannot use their limbs to engage in battle, yet already they bear off the palm of victory.
-- From a sermon on the Holy Innocents