the_debt_of_time

"Like I said, you fainted," she explained, running her fingers through his hair,
moving her hand away when he went to grab it. Sirius glared at her when she pulled from
him.
"So, if you aren't pregnant," he said the word on a sharp exhale of relief, "and you're
not sneaking around with Remus behind my back.. ." he added, as Mia tossed him her
best look of deep loathing at the mere suggestion. "I said you're not, so stop with the evil
eyes. After everything we've been through, I actually trust that if you still had feelings for
him, you'd just tell me." He sighed and leant back into the pillow, letting her rub his head
in peace. "Why are you still keeping things from me?"
"I've kept this one from everyone," Mia admitted. "Not even Jamie knows."
Sirius's eyes widened. "How bad?"
"I'll be making you all take a Wizard's Oath before I tell you," she told him, hoping
that would imply the severity of the situation. "But you should know that my secret
has nothing to do with you. You are not in any way responsible."
She knew that Sirius had long ago blamed himself for the scar on her ribs.
Inadvertently, she had admitted that he was involved somehow, which was the truth. This
scar, however, was different. Sirius—older Sirius—had nearly gotten himself killed trying
to prevent it from happening, and she would not have his younger self thinking he was
responsible for it.
Twenty minutes later, her friends and Peter were gathered in the boys' dormitory
where the door could be locked. Mia cast a quick Muffliato Charm, just in case, before
insisting they all take a Wizard's Oath. Predictably, James was the first to offer his wand,
swearing secrecy upon his magic, followed soon behind by Sirius, Remus, Lily, Alice, Frank,
Mary, and, eventually, a hesitant Peter.
"Some of you already know this. I'm adopted," Mia whispered, catching the
surprised looks on Alice, Frank, and Mary's faces. Peter stared at her for a long while as
though he were trying to add it all up in his head. "I was a Muggle-born," she explained
and watched his reaction go from confusion to surprise to irritation and mild disgust.
And there it is, Mia thought. A pureblood Slytherin girlfriend for a few months and he's already
slipping. However, Peter's prejudices and damaged soul weren't her concern just then. If it
would not have looked suspicious, she'd have preferred him to not be included at all; as it
was, only his Wizard's Oath was keeping him involved now.