I am not trying here to defend the kiss or defend Sebastian for what he did.
I am here to explain this. Look I know we are all like: ugh wth?? but the thing is I think that was a clever thing to show it. I know, I know, let me explain.
It is kind of understandable in a way. This kid who has demon blood, who never in his life understood what is love. He does not know the difference between couple love or family love. He does not understand this feeling he has with Clary. This girl defended him, humanized him and said things that he never heard in his life.
I mean, what would be his interpretation of that if he never learn about it? That was the point in the books. The fact that this twisted demon never knew how to interpret love or what it means so he just lets his primal side determinate that. The side that is physiological, that does not have any logic. Like if we use Freud’s example, he uses the id part of his brain and there is not super ego involved to determinate what is right or wrong.
It is pretty complex concept. And before you start hating on the show because of that, then don’t watch it. I don’t understand why you want a show that is so simple and superficial. Isn’t it great when the villain becomes complex? isn’t it great when a show shows smart writing?
That is the point of villains like the Joker from batman. The fact that we try to think why they behave that way because they are so complex is what makes them great villains. It does not mean you need to support their decision.