Declan has done this before plenty of times. Sometimes for his own desire, wanting to touch and taste a cock, but more often he's done this for power. Grades, influence, blackmail... sometimes the easiest way to get something done is on his knees. He's never done this out of affection. He doesn't go down on his girlfriends. That's not the kind of relationship he has with them, and they all instinctively seem to know it.

So when he takes Gansey into his mouth, bobbing his head with professional precision, it isn't a gesture of affection. It's something he knows how to do, a way to offer pleasure and create debt without giving any of his own vulnerability.

The sounds that Gansey makes are sweet and lovely, something to admire, but Declan carefully locks it away to enjoy later, in private or perhaps never.

Declan doesn't know how to do this with intimacy or vulnerability. It's only something to be given, a favor for Gansey which creates a sort of debt, a hint of blackmail that he can use later whenever he wants to end a conversation or stop Gansey from pressing. Later, he thinks, this will be something for Gansey to regret. For Declan, it's simply a task to complete.