Fic: Mother's Day by TheFirstMrsHummel
At the beginning of senior year, a strange woman shows up looking for David Karofsky. Kurt helps her find him, and finds out something about Dave's past along the way.
Chapter 4: http://www.fanfiction.net/s/7014708/4/
Chapter 4: http://www.fanfiction.net/s/7014708/4/