Here's another scenario. It's from Law and Order SVU so yes it's a TV show but relates. When Olivia Benson was kidnapped by William Lewis he incapacitated her. Put her in the back of a car and kept her drunk and drugged while he took her somewhere to probably rape her. Sadistic character. They got to an empty beach house. He handcuffed her to a bed. At some point she broke loose. She handcuffed him to the bed and eventually she brutally beat him because he instigated her to do it. He was subdued at any point of his many injuries (as he brings up in court later). I doubt she thought once she got free she would kill him. But he got into her head and she snapped. Beat him nearly to death. Eventually I think she got brought up on excessive force because at first she lied about it in court.
I was giving an example to show when self defense goes overboard. There's another. But you can't say there is intent. Not to start with. She didn't intend to kill him that day or when he kidnapped her. You can't predict human emotions in a situation like that.