Warnings: Explicit sex, threesome, set in Purgatory. Spoilers for Season 7.

Castiel had learnt a lot of things from his interactions with humans. He had learnt about love, about kissing, about lust, and about many other things an angel wouldn't even think about, things he had never imagined when he met the Winchesters for the first time.

And yet here he was, caught up in the middle of what probably was the most bizarre relationship in the universe.

He called it relationship, but he wasn't even sure what it was himself. There was always a spark between the angel and the hunter, and then the vampire came along to ignite the fire. And boy, did it light up.

Hunting, running, kissing, touching, fucking, fighting, more running... it became a daily routine in Purgatory. It didn't help that Cas and Dean were the most popular guys there, so every monster wanted a piece of them. The time was short and precious, but it was worth it. There was a moment for fighting for their lives, and there was a moment for pleasure and passion. Initially, Cas had trouble identifying which was which.

But it wasn't the fact that he was in a three-people relationship what bothered the angel. It was his past, the things he had done on Earth. His alliance with Crowley, claiming to be the new God, murdering all those angels who opposed him, letting the Leviathans loose... his sins accompanied him everywhere he went, and he just couldn't let them go.

Dean noticed it. Sort of. He could see Castiel was more distant, kept to himself, hiding away from him and their new partner. Benny didn't notice it, but he didn't know the angel as well as he did. When Dean touched his body, Cas reacted, but not as excited or lustful as Benny. Sometimes he didn't even participate, and claimed that he needed rest, or kept watch for monsters.

But Dean couldn't do much about it. He had tried talking to Cas more than once, but the angel never revealed much. The only moment they had for a break, for pleasure, and he spent it resting? Something was not right, he knew that much. But if Cas didn't want to tell him, it was his loss, or at least so thought Dean.

And with that in mind, Dean returned to Benny's arms. The vampire and the hunter had a strange connection. They didn't trust each other completely, but some trust had built up. They had each others' back against the other creatures in Purgatory, and Dean trusted that he wouldn't bite him as he allowed the vampire to sensually kiss his neck.

As he rested from the last fight, Castiel could hear a moan. Dean's moan. Jeans were undone and tossed to the floor as Benny continued to kiss Dean's neck, playfully touching one of his nipples with one hand. The other was busy with his cock, caressing it as if it was the first time. Dean's gasping told Cas that he was far from displeased with his actions.

It wasn't that Castiel didn't like Dean or Benny. They were certainly pleasant to his eyes; their looks, their body, their charisma... but no, he couldn't. Every time Dean's lips got closer, or Benny undid his shirt, all Cas could think of were the reasons that led to his stay in Purgatory, the sins and treason he had commited. And that, certainly, was no turn on.

So it came to a point that he couldn't even get into it anymore. There was always a reason; monsters could return, he as tired, he was injured from the last battle, he needed a minute for himself... those excuses were weak, he knew it, but it was all he could come up with. And he could notice the effects of his decisions, as Dean and Benny got closer, spent more time together, had sex only the two of them more often...

It was good, Cas told himself. He had sins to pay for, and if that price was to stay out of that "relationship" the three of them had, he would pay it. Even if it meant giving up on something that could make him feel so good.

Castiel stood up as he heard Benny reach orgasm. Dean came almost immediately afterwards. Cas could hear a snarky comment from Benny and Dean's "shut up" in response, but that wasn't what he was trying to hear. It came from afar, but he got it and had quite a good idea of what it meant.

"Werewolves" the angel said, heading towards the other two. "We must leave immediately."

The two of them agreed, and in the blink of an eye they were ready to go. The small group parted, and yet Castiel still thought of what he was trying to leave behind, unable to stop thinking about the penance he was doing in Purgatory, and if it was truly ok to seek a way out with Dean, with all he had caused...