Yellow.
"She likes you, and you like her. You're besotted. Ask her, Neville, before someone else does."
Neville slumped his shoulders.
"I've got nothing to give her, Harry."
"This is Luna we're talking about, what do you think she wants? You defeated an army, Neville; brought one of the most evil wizards to his knees, without a thought for your own safety. You did it to give us all a chance ... Give yourself a chance, Neville. She really likes you, too."
He was silent for a while, before he nodded.
"I'll try, Harry."
Harry folded up the parchment and sighed. In two days time he would be attending the engagement party of Luna Lovegood and Rolf Scamander.