Nes had a huge argument with Seth. Jin could hear it from downstairs. Seth and Nes were in Seth's office. Nes was yelling at him. Seth was trying to calm her down. The argument was mostly one-sided as Nes was doing all the talking.
"You fucking fed me aphrodisiac!"
"I did not. Can't you see that you truly wanted me? I don't have to rely on aphrodisiac to have you," Seth said rather calmly.
"You bastard!"
Nes was violent. She had the tendency to get physical when she was too angry. She once scratched Theo's face so hard that she drew blood.
Jin heard the sound of throwing something made of glass against the wall. Then the sound of a slap. He had to admit that Seth deserved it. Not just this. He deserved things far worse.
Okay, it's true that we are not sure that he is using those things on Nes. But seriously, why else would she behave like that? Like a completely different person?