Lily and Peter bonding over being plus sized in a conventionally attractive friendgroup??
Whenever one of their friends goes to judge a mean person by their weight first, they give each other a little look
"Do these jeans look fine-you know what, nevermind, I'm going to go ask Lily."
Sirius complaining about how the Hogwarts food is going to make him gain weight (he's got his own issues regarding food) and Lily angrily ranting about it to Peter later, how for some reason people's greatest fear seems to be looking like them.
Peter helping Lily understand how beautiful she is, hyping her up in her outfits, complimenting her, because she's gorgeous and deserves to be told how pretty she is (don't worry, Mary and Marlene hype her too ;) )
Them bonding over things like having a harder time shopping for clothes, getting chosen last in sports activities, or having to put forth a strong personality to make a good impression, since pretty privelege apparently won't carry them through
Peter struggling with his body image more than Lily because she's been surrounded by Mary and Marlene, where he has James, Sirius, and Remus. Not that they're mean, but Sirius and James tease him a bit and it's a vulnerable subject so he doesn't bring it up to Remus, as much as he knows Peter well. He feels a lot safer talking to Lily, knowing she understands. And she does.
It's not much, but it helps. Knowing someone else understands.
I FEEL LIKE THEIR FRIENDSHIP HAS SM POTENTIAL
