the arms behind its back OMG!
Just imagine Neville taking Luna to St. Mungo’s to meet his parents. At first he is a little nervous - not as much as his grandmother though, she rather keep those visits between her and her grandson - but as it turns out, there is no need to worry.
Even the doctors and nurses are touched and impressed by the gentle and unabashedly open way this peculiar, young girl has with them. Especially Neville’s mother quickly developes a particularly strong bond with Luna. It’s probably the closest she has come to making a real friend in seventeen years.
They play easy boardgames - it turns out Luna never threw away any of her childhood toys - and miraculously Alice never loses. They learn how to fold little birds and butterflies out of candy wrappers and Luna makes them fly around the room, while Alice watches with a beaming smile on her face. Luna tells Alice all about her own mother - how she died and how much she still misses her every day. She tells her about her life with Neville ("He’s going to be a great professor some day. He still doesn’t believe Nargles live in mistletoes, but dont worry, I’m working on it."). One day, as they are saying their goodbyes, Alice surprises them all by suddenly engulfing Luna in a tight hug. Neville doesn’t lose any time and proposes on their way home.
And this is why to me Neville / Luna is the best alteration of book!canon in the history of movie adaptions.