Remus would usually try to be positive about being a werewolf but he would occasionally become reclusive and angry, especially nearer to a full moon.
One month he's had enough. He was so frustrated and angry at everything to the point where he refused to speak to the rest of the Marauders. He didn't feel like he deserved to be their friend, he didn't feel like he deserved to be anything.
He closeted himself in their dormitory and wouldn't leave or speak to anyone no matter how hard they tried until Sirius, who usually just let people get over their problems on their own, finally got fed up with him.
He slammed his way into their dormitory, walked right up to the edge of Remus' bed and stood, arms crossed, glaring down at him
When Remus still refused to acknowledge him Sirius punched him hard in the shoulder.
Remus toppled off the bed and gaped up at him, shocked at the hostile expression on his face.
He scrambled to his feet, rubbing his arm indignantly.
They glared at each other across the bed until Remus, very unwisely, said "What?"
This only seemed to infuriate Sirius more.
"What? WHAT?! What the bloody hell is your problem you git? Moping around for days, not talking to us." He scowled. "You're being a complete pain in the ass! So how about you stop being such a miserable dick and tell me what the hell is wrong before I beat you down."
Remus held his glare for one long minute before sighing and looking down ashamedly, "I can't be friends with you anymore."
"And why would that be?" Sirius asked, mock-politely.
Remus tried to keep calm; he hated it when Sirius used that condescending tone.
"Because I'm a monster, I'm not fit to be around human beings, I'm surprised you, James and Peter haven't been torn to shreds yet! I'm so ashamed" he gripped his hair, and then dragged his fingers roughly through the knots that had accumulated over the past few days, in frustration.
"You think that being a werewolf is something to be ashamed of?" Sirius said in a quiet, deadly voice that filled Remus with an unusual sense of foreboding that didn't quite fit with the easy-going image Sirius tried to uphold.
His eyebrows furrowed as Sirius, without another word, pushed up his sleeves aggressively and held out his bare arms, Remus gasped.
There were deep, angry, red welts travelling the length of his arms, the occasional burn punctuated these scars that interspersed randomly across his forearms.
"Gifts from my mother and father for being insolent."
"I don't-"
"You see" He interrupted loudly "they only ever make scars by dark magic on skin that can be covered or everyone would know their son wasn't right and they'd look weak" Sirius spat. "You think something you can't control is something to be ashamed of? Does that mean I should be ashamed of my scars like you are of yours?" Remus sputtered incoherently unable to express his horror."Because I'm not. I'm proud of these scars, every one of them represents a time that was scary and violent but they also represent a time I survived against the odds... and it's the same for you. You're not a monster Moony, you're a survivor. Something bad happened to you but you always come back from it and come back to us, just like me. We all have our demons and have to fight our own battles but it's what makes us who we are. You're a good person Remus; don't let this one bad thing about your life ruin the rest of it."
Sirius turned to leave but right before he reached the door Remus called out softly "I'm sorry Sirius" Sirius turned to look at Remus, still standing by his bed "about how I've been acting and about everything that's happened to you. I knew it was bad at your house but I never would have guessed... I've been so wrapped up in my lycanthropy I didn't see my friends had their own problems."
"You really should work on that" Sirius said, attempting a joke which Remus smiled weakly at.
"Thanks Padfoot."
"What are friends for if not to share emotionally scarring stories about their lives? By the way if you tell James or Peter I will have to tie you by your ankles to the Whomping Willow" Sirius grinned.
"You really should tell them" Remus said frowning.
Sirius sighed "I will eventually. Just give me some time. I know James will lose it when he finds out so I'm building up to it. So only you can know for now, can you keep this secret for me?"
Remus smiled ruefully "Always."