I also found out that:

"At one point in their third year, Hannah was convinced that Sirius Black could turn into a flowering shrub (PA9), which in hindsight is less silly than it might sound at first. House loyalty had her wearing a Support Cedric Diggory! badge early in the Triwizard Tournament (GF19). Despite occasional incidents like this, she and Ernie are on friendly terms with Harry, Ron, and Hermione."