Sirius groaned as Harry's strokes quickened. They pressed their foreheads together, leaning against each other in their struggle to remain standing. Harry's cock was slippery in Sirius's fingers.
"Getting close," Harry panted. "You?"
Sirius nodded. "Are you sure about this?"
"Yes," Harry breathed. "For the twelfth time, yes."
"Just asking... fuck..." Sirius sucked in a breath. "God I love that thing you do with your fingers."
"This?" Harry asked, and did it again.
"I'm going to... do you have it?"
"Yes, hang on."
Harry tugged Sirius's cock down at an awkward angle, which pulled him back from the edge a bit.
Sirius slid his free arm around Harry's back. "Are you close?"
"Yes," Harry said. His eyes were closed. "Oh, yes."
They came within seconds of each other. Harry somehow had the presence of mind to catch it all in the small tupperware container in his hand. Sirius was still shuddering when Harry snapped the lid shut and tucked the container under his shirt to keep it warm.
"Are you going to tell them?" Sirius asked.
Harry tugged his trousers up with one hand and shook his head. "No."
"They wanted you to be the father, not me."
"They won't know any different," Harry said, leaning forward to kiss Sirius. "But we'll know. It'll be our baby this way."
"If Ginny ever finds out--" Sirius began.
"She won't," Harry said, his voice firm. "Don't worry."
Harry disapparated to Ginny and Luna's flat. Sirius sighed.