Harry Potter and the quirky aura specialist

Hermione and Ron had dismissed his claims when Harry told them his suspiction about Draco Malfoy being a deatheater. What if Harry had shared his conviction with another friend who not only believed him instantly but also decided to actively help him? This story starts at the middle of Harry's 6th year, at Slughorn's Christmas party. Alternate Universe(AU) story. Harry/Luna.