I read this fic awhile ago...

It started with Dean acting odd (Cas and Sam notice early and are worried) and soon showing traits of turning into a demon. I think Cas had suppressed the the side of Dean that had turned demonic wile dean was in the pit?
Dean gets out of hand and so Cas calls Gabriel for help. I remember when Gabe gets there Dean has almost lost himself to the demon, the demon even starts calling himself by another name.
The only way to save dean would be to rip away the demonic part of it. So Gabe basically rips apart Deans soul.
Deans too weak to go back into his body after they destroy what was left of the demon so Gabe keeps Dean safe in his grace to heal.
Dean stays in Gabe's grace for long time and Gabe even began to develop feelings for Dean. Towards the end of the story I remember that when they put Deans soul back in his body he turns out to be half angel now! Or at least has wings.
Last little tid-bit I remember is that when Gabe confessed his feelings about Dean to Cas it was reveled that Cas had strong feelings for Sam.

Thank you so much for helping me find this story!

This is my first time posting so sorry if I did something wrong...