Lily's tongue terrifies. Her sharp insults (just a joke, right? Can't you take a joke?) should leave her with no friends, and yet she's adored. She doesn't know when to stop. She laughs at everyone equally (why shouldn't I laugh? It's funny!). She points and she preys and she's petty.
She seems so very thick-skinned. People joke back, of course, but Lily can never let anyone else win (it's not like you're known for your character). So she fires back, raises the heat, and keeps going until they back down. They always do.
Coward. You're not afraid, are you? Idiot. Fake. Unloved. Is that why your boyfriend left? The words that are her regular weapons are the ones she's most afraid of. Who ever heard of a Gryffindor who was scared? That's not her at all. She's invincible, perfect Lily, haven't you heard? You'll never get the best of her.
But pride comes before a fall. Everyone knows that, even Lily.
She lives in fear.