The only time Draco ever calls Connor "brother"; the younger twin has just sacrificed himself to save both Harry and the wizarding world.
In book six, we learn that Hawthorn Parkinson's garden contains a hawthorn bush sheltering a clump of dragonsbane and some small pansies. Dragonsbane and Pansy are her husband and daughter respectively, who are both dead by this point.
Book seven, Intermission: Snapshots. The whole thing, really.