James and Remus never saw it.
But Sirius did.
Sirius saw the looks.
Heard the muttering.
He knew.
And the morning he called Severus that filthy name, Sirius was at his throat the second he got the chance.
Severus heard too.
He gave the rat a cold, half lidded stare.
Severus would kill him if he wasn't Sirius' friend.
That was clear, he was the rat and Snape was a boa, ready to crush him without a seconds thought.
He'd left the room, going to retrieve a snack and Sirius excused himself.
It took him a second to grab him by the hair, spin him around and pin him by the throat with his arm.
Sirius radiated fury.
He showed his teeth.
His gums.
Flicked his tongue across his teeth openly with the words that seethed out.
"Sirius!"
"Call him it again."
"W-What?"
Peter was terrified.
His heart thrummed in his ears.
He shook violently.
"Don't fuck with me. You called him a faggot. Am I a faggot?"
"N-No!"
"I put Severus before me. James puts Severus' safety before his own and he knows without a doubt I'll do the same for him and Lily. We're brothers he and I. It's a pact. We protect our mates and we'll crush anything we find threatening. You understand? James might not have noticed yet and you better hope he fucking doesn't."
Peter knew it. He knew when it came to their friends he was at the bottom of the food chain.