Alexander left the palace without letting anyone know and rode to the place where he first met Francis, he had a lot on his mind. His father's death was something that he had not anticipated happening at all.
The poisoned water couldn't have been a coincidence after his fight with Olivia, as much as he didn't want to believe it. He was very sure that she was responsible for everything that was happening. He had always had a soft spot for her that he overlooked the small things she did but her wings were growing a lot. She was getting more dangerous with every day.
It hurt him that the girl he considered his best friend would go as far as this just to get even. She is so greedy for power that she sacrificed his father in the process of it all. He regretted never listening to his mother and leaving Olivia. She was a human but had a heart of a wicked witch.