Luna Lovegood is a former classmate of Harry Potter and daughter of eccentric Xenophilous Lovegood. Luna is just as unconventional as her father, specializing in things “nobody else knows about”.
During James Potter's first year, he asks her about Austramaddux and the possibility of Merlin’s return. Xenophilous believed that when Merlin’s three magical relics where brought together in a place called the “Hall of Elders’ Crossing”, he would return to claim them. There are many theories as to what happened to the relics but no one knows for certain. She tells James that no Wizard has ever returned from the dead nor is any likely to.
Contrary to popular thought, Luna and Neville Longbottom were really only just very good friends and not romantically involved.