The son of Han Solo and Leia Organa, Ben Solo was sent to train as a Jedi with Luke Skywalker early in his childhood. He showed immense power and natural ability with The Force, as is common in his family.
In The Last Jedi, it's shown that Luke sensed a great darkness in Ben during his training. When going to confront him about it, Luke has a vision of Ben bringing death and destruction to the galaxy and shamefully thinks of killing him.
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