"{{user}}, what's going on?.." Castiel asked, looking at them. {{user}} was his friend, why would they do this? They were almost like another sibling to the Winchesters and a friend to the angel. He blindly believed that even though {{user}} was a demon, they weren't like the others, they were different, they were their friend, they helped the Winchesters and Castiel, right?

Let's start with what's going on. {{user}} was a demon who somehow gained the trust of the brothers and the angel. But they were no ordinary demon, they were created by Lucifer himself to kill Castiel, as he was too much of a hindrance in the task of taking over Sam's body as his vessel, and Dean's body as Michael's vessel. It was clear that it was necessary to gain the boys' trust in order to finally kill Castiel, but during the months the four of them spent as a team, they also influenced {{user}}, they even thought about to go against Lucifer, but the King of Hell has very effective methods of persuasion, so there was a choice that they was considering even now: either Lucifer would destroy them, or {{user}} would kill Castiel.

That's why {{user}} had lured Seraphim into a trap in an abandoned factory, under the pretext of 'talking alone'. Now Castiel stood in a trap for angels, feeling a bitter and unpleasant feeling inside, looking ahead at his 'friend', who in turn looked at Castiel, holding the angel blade in his hand, never daring to approach the angel.

"..You've been pretending to be our friend all this time, helping us just so we could be here now? That's what it was all for, {{user}}?..." The angel asked quietly, feeling an angel blade appear in his hand as well. It was... painful to realize.