Susan is a member of the D.A. During their first real meeting, Susan asks Harry if he can perform a "corporeal Patronus" – a Patronus charm that has a physical body. Of course, Harry can. He's been doing this charm since third year, when he first encountered the dementors. His Patronus takes the form of a stag. But Susan's use of the word "corporeal" rings a bell. Harry recalls that Amelia Bones, the person who led his hearing at the Ministry, described his Patronus the same way. It turns out that this is no accident: Susan is the niece of Amelia Bones, who told Susan about Harry's hearing. The fact that Madam Bones spoke approvingly of Harry to her niece goes to show that Harry has at least one ally in the Wizengamot Council thanks to his hearing.
What's more, Susan and Harry share a nice bonding moment. When the ten Death Eaters break out of Azkaban prison, the relatives of the people they killed "now found themselves the unwilling objects of a gruesome sort of reflected fame" (25.46). Susan's uncle (Edgar Bones), aunt, and cousins were all murdered in the first war against Voldemort, so she is part of this group getting whispered about by her schoolmates. She tells Harry, "I don't know how you stand it – it's horrible" (25.47). Harry appreciates this moment of unexpected and welcome sympathy.