Setting: After Deep Water, and some time during season 2. Cordelia's POV.
Hatred
She watched as he stalked towards the other man, fury and anger and rage and pain all waring for dominance in his expression. And as he drove a fist up to meet the others jaw, she remembered a conversation she'd once had with Giles in the library.
"You don't get over that sort of betrayal overnight. Love removed so suddenly, seems to demand an equally strong emotion to replace it."
He slammed the others head down, and bought up a knee to meet his chin.
"Like hatred."
She watched as Ethan hit the floor, chuckling weakly, in spite of the beating he was taking.
At that time she had wondered how someone like Giles had known about that sort of thing. But now there was no mystery to it. She could guess. Once upon a time the Watcher had loved him.