Summary: "There is someone there. Someone watching us. I can tell. There, over by the bushes."
(Hermione Granger to Harry Potter, Christmas Night 1997, graveyard in Godric's Hollow)
Christmas 1997 story, compliant to DH 1st half. My guess as to the person hiding behind the bushes? Professor Severus Snape visiting Lily Evans. The story is Snape-Potter mentoring one.