Pensieve

Remus Lupin was returning to Grimmauld Place when he realised something was wrong. It was the same sense of premonition he had had 15 years ago. He tried pushing it aside but too late, dark thoughts were already racing through his head.

"Sirius!", He burst into the house.
"Moony? Moony!," Sirius emerged from the kitchen. Relief washed over Remus.
"Something's wrong," Sirius said. His stomach sank.
"Wh-what's wrong?" He spluttered. "Is everyone okay? Tonks? Molly? Arthur?"
Sirius shook his head. Remus felt his stomach plummet further.
"It's Harry. I think he's gone to the Department of Mysteries...I believe he has been tricked by Voldemort himself."

Remus was firing away spells, one after the other, his wand making slashing movements. He had an eye on Harry, who was trying to help Neville up the stone steps with his wiggling legs. He was also watching out for Tonks and Sirius. It appeared Harry still had the prophecy on him. Remus ducked to avoid a spell, and that was when he heard Bellatrix's mad cackle.

Remus turned, everyone seemed to have momentarily paused their dueling. Time slowed down. Sirius's expression changed from amused, to shock, to fear, and then it froze. His whole body froze, his wand clattered to to the floor, his mouth half open in a laugh, but his eyes wide with fear. Remus thought he could see the hint of a tiny smirk play across Sirius's lips. And then slowly, very slowly, he fell. He fell behind the veil, gone forever.

"NO!" Harry yelled, and lunged forward, as if to stop his Godfather from falling. Remus was snapped back into reality. He grabbed Harry, trying to stop him from going after Sirius. Harry kicked and yelled, screaming in agony, his cries matching everything that was going on inside Remus. He could feel his heart break into a million tiny fragments, not just for the loss of his brother, but for this unfortunate boy, who had lost the one person he had come close enough to consider him as his father.

That day, Remus Lupin broke, but he held on, for Harry.