Mathew N. Schmalz said this quote

Mercy is God’s loving response to sinners; and mercy is our loving response to others—and to ourselves—in circumstances of need. To this I would add that mercy, as an experience of love, has an unexpected quality—something unforeseen or unanticipated. We talk about mercy when we feel or offer forgiveness, when we find or give help and assistance, but we also speak about “mercy” when we are surprised by good deeds that catch us unawares and transform our lives for the better.