Disclaimer: I don't own Supernatural, or Balthazar or Castiel. Or the song from which the title was taken.

The title comes from Martyn Joseph's song Turn Me Tender: "the pledge and the vow is 'you find if you seek', but what if you try and find nothing but bleak?"

Balthazar watches as Crowley strides out the door, disappearing into the thick black smoke. To anyone else, Cas seems to be left on his own – and judging from the look on Cas' face, he seems to think that too. Balthazar knows he should reveal himself, but if he did that, he'd have to say something, and even if he had something to say, he's not sure he'd be able to get the words out. After all, what do you say when you find out that the only one you've trusted unconditionally since the beginning of your existence, since before you even knew him...what do you say when you find out he's been lying to you?

So Balthazar leaves too. He goes to a place in Heaven – his favourite retreat. He stands on the sand, looking out at the sea as the waves battle the cliff side. The rain hammers down, soaking him to the bone in an instant. It's freezing against his skin, but he doesn't mind. The dark skies flash with lightning and a clap of thunder sounds somewhere in the distance. The chaos around him makes him feel strangely at ease.

He flies to the cliff top. The sudden firmness of the rock beneath his feet takes a few moments to get used to. He remembers the first time he came here. He had stood then, just as he does now, at the top of the cliff, staring out over the vast expanse of nothing but sea and sand and sky, feeling the rain and listening to the thunder, savouring the restless hush that enveloped him. He had known for certain then that he would come back here, and he did, so many times. Eons passed, and he visited so many different Heavens, but none of them had ever matched up to this. Even Cas' eternal Tuesday afternoon never made him feel the same kind of peace he felt here.

He remembers the last time he came here, too. It was just before he'd left Heaven. It was the final place in Heaven he had visited; a desperate attempt to remember his home as a place of beauty and peace, devoid of war and fighting and cynicism. It hadn't worked. Looking back, his naïveté was almost laughable, and so unlike him.

And then there were the times in between. Thousands of them, maybe even millions – too many to count. Only one stands out in Balthazar's mind: the first time he had brought Cas here. He'll never forget the look on Cas' face that day – anyone else would have been surprised that this is Balthazar's favourite Heaven, but not Cas. He had only nodded. No questions, not even a wordless gaze of curiosity. Just a nod, and a tiny smile, barely noticeable. And then they had just talked. About everything and about nothing; about life and death, Heaven and Earth, angels and humans. About God, His creations, His plans. About peace and war. Right and wrong.

He hears a flap of wings behind him. It sounds so loud, even over the noise of the rain smashing onto the ground, and the wind howling around him, and the thunder rumbling above him. He doesn't need to look to know who it is.

"You were there, weren't you?" says Cas.

Balthazar doesn't answer.

"You were watching. I could feel you."

"Yes," says Balthazar. The wind starts to die down, and the rain turns to a shower. The thunder fades into the distance. Balthazar feels Castiel's gaze boring into his back.

"Why did you stay hidden?" asks Cas. Balthazar can tell by his tone that it's a genuine question, not an accusation.

Balthazar shrugs. "You had the Winchesters to deal with. That's more than enough for anyone. How are they, anyway? I take it Dean is sulking somewhere after your little lovers' tiff."

"Stop it." Cas' tone has no authority, but Balthazar doesn't say anything more. He flies back down to the sands and in less than a second, Castiel is there too, still standing a few feet behind him. Balthazar starts to walk along the beach, and Cas follows him. In silence, they follow the never-ending shoreline, heading towards a horizon they both know they'll never reach. It's something they've done a thousand times before, but then the silence was comfortable, because there was nothing that needed to be said. This is different. They're silent now because there's nothing that can be said.

Balthazar never thought he'd see this day. The day when everything changes between them. The day when neither of them knows how to fix it. But nothing lasts forever. It was foolish of him to think it would.

"That's not true," says Cas. Balthazar realises he's been so wrapped up in his own thoughts that he didn't even notice that Cas was reading his mind. He turns around, finally looking at Cas. He's staring at Balthazar with wide, sad eyes. He looks so lost and helpless, and in that instant, all of Balthazar's feelings – the anger, the bitterness, the betrayal – push themselves aside. They're replaced only by an ache, heavy and burning inside him. So much is there that was never there before, but none of it's right. Something crucial is missing.

"Things don't have to change, Balthazar," says Cas. Balthazar's not sure how much Cas believes that. It sounds more like a plea than a statement.

"Why didn't you tell me?" asks Balthazar. His voice is calm and steady, and it's not hard to keep it so.

"That I was working with Crowley? That I had made a deal with the King of Hell? I'm sure you would have taken it very well."

Balthazar sighs inwardly. Sarcasm. Cas has been spending far too much time around Dean Winchester.

"You told me about using the souls," says Balthazar.

"I told you everything you needed to know."

"You lied to me."

"If I'd told you about Crowley you would have - "

"I would have stood by you."

Cas falls silent. Balthazar stares into his eyes, and takes a step to close the space between them. Droplets of rain linger on Cas' eyelashes. One falls and traces a path down his cheek. Balthazar reaches out his hand and brushes it away, his hand coming to rest on Cas' shoulder.

"I would have stood by you," Balthazar repeats, softer.

"I'm sorry..." says Cas, his voice wavering. "I'm sorry."

Balthazar, his hand still resting on Castiel's shoulder, feels the ache inside him grow heavier, and he suddenly realises what's missing. It's Cas. It's his own grace that he can feel, and it's screaming out for something that's been torn away, something that's been a part of him for so long that Balthazar feels incomplete without it. In a fleeting moment – of horror, regret, or maybe sorrow, he's not really sure – he wonders if this is what Cas felt when he thought Balthazar had been killed.

"So am I," says Balthazar, his hand moving up into Cas' hair, fingers combing through it slowly. He flies them both up to a small cave hidden in the cliff face. Looking out at the horizon, he feels uneasy. It seems so close now.

Turning his gaze back to Cas, Balthazar takes his hand away, letting his arm drop to his side.

"Everything's spiralling out of control, Balthazar," says Cas. His tone matches the utter helplessness in his eyes. "I thought I could handle it; I thought I could contain it. But I can feel it, it's strong. I think it's too strong."

"What is?"

"I don't know..." says Cas. "It...it scares me."

"It's OK," says Balthazar. "Cas, it's OK."

Cas shakes his head. "No, it's not." He reaches into Balthazar's jacket and takes out the angel sword. Gently, he presses the sword into Balthazar's palm and closes Balthazar's fingers around it. The silver is cool against Balthazar's skin and it sends a shiver through his whole body.

"If I go too far - " begins Cas.

"No." Balthazar cuts him off. "Cas, no. Don't be stupid."

"Balthazar, listen to me."

"No."

"Please."

The look of pure desperation on Cas' face and the crack in his voice make Balthazar fall silent. He looks down at the blade clutched in his hand, Cas' fingers closed around his own. The metal seems to glint and shine even in the darkness of the cave. It's so much heavier than he ever remembers.

"Don't let me become something I'm not," says Cas. "If it comes to it...it has to be you that stops me."

Cas' grip on Balthazar's hand and the sword loosens. Balthazar knows Cas is staring at him, waiting, pleading. But Balthazar keeps his eyes fixed on the blade. He knows he would turn it on himself a thousand times before letting anything hurt Cas, but he nods anyway. Cas takes his hand away from Balthazar's. It seems to be enough.

Balthazar lets his arm drop and the sword hangs at his side, his hand loosely holding onto it. He leans his head against Cas' so their foreheads touch. As he wraps his other arm around Cas' waist, he feels Cas lean into his touch, and the ache inside him starts to fade. Balthazar's not sure what will replace it, but right now he doesn't care.

His heart skips a beat when he feels Cas' hands come to rest on his upper arms. The touch is so gentle, almost weightless, that Balthazar is sure anybody else wouldn't even have felt it.

A blinding flash of lightning illuminates the cave, and thunder rumbles above them. The rain gets heavier and in only a few seconds, it's lashing down from the almost black clouds, hitting the ground with unapologetic ferocity. Balthazar can hear the waves shatter as they crash against the rocks below. He glances out at the horizon line. He can barely see it through the rain.

He starts to wonder if he wasn't being naïve after all. Maybe some things do last forever. Maybe anything can last forever, as long as it can last until tomorrow.