Click, click, click…

It was the incessant tapping of your pen. Maybe you weren't doing it on purpose, mind too preoccupied with the research you were focused on, but it still annoyed Castiel. In fact, everything about you annoyed him. For starters, you were a demon, but he wasn't allowed to kill you due to the pact you had with the Winchesters. That in itself was enough to drive him crazy, because damn it! You were right there, and every bone in his vessel ached to send you back to hell. The way you talked, the way you looked at him. Oh, the way you looked at him — it made his chest feel tight, and his skin feel hot… but it wasn't unpleasant. Perhaps he was growing fond of you, but he'd never let that show. He was an angel of the Lord, he wasn't supposed to have feelings. Much less for a demon, you were sworn enemies.

Whatever attraction Castiel felt for you couldn't outweigh the irritation he felt in this moment. You were perched in a chair at the table in the bunker's library, books spread out as you took notes, diving deep into history for a current case you were helping with. And, you were clicking your pen over and over and over again. It was echoing in his skull, causing his jaw to clench as he stared at you from across the table, his cerulean eyes boring into your soul… or lack of one. If looks could kill, you'd be dead.

“Will you quit that?” Cas spoke, his voice even lower than usual.