It had to be done.

That simple truth doesn't make this any easier. The acrid scent of burnt feathers sears the back of his throat, and Dean thinks he's going to be sick. He takes a deep, steadying breath that almost breaks loose into a wail. Just almost.

His eyes are fixed on the twin black marks burnt into the pavement. Those outstretched wings – the reminder of what used to dwell inside the now dead and empty husk in front of him. Something that had been impossibly beautiful and otherworldly. Now gone. Erased. Annihilated.

"Dean..." Sam places a hand on his shoulder, to comfort his brother. But instead, he clings to him, desperate for his big brother to make this right.

But there will be no making this right. Ever.

In that very last moment, it had been Castiel staring back at him through familiar blue eyes. As Sam had done before all those years ago, Cas had subdued Lucifer for a few brief moments. Buying them the time they needed. Making it so Lucifer couldn't stop what was about to happen.

"I'm sorry," he had mouthed, accepting what was to come.

Because it had to be done.

But in the end, Dean hadn't been able to do it. Claire's hands are still gripping the hilt of the angel sword buried in the dead vessel and her shoulders are shaking violently from her sobs. It's barely audible, but she's been repeating the same thing over and over, like a mantra. Like a prayer.

"You promised...you promised..."

Promise me you'll take care of him. He's been through enough.

"I know I promised, kiddo," Dean mutters bleakly to himself. "But I lied..."