Alright, kiddies... put on your Infinities hats (mine has a beanie!) and let's use our imaginations for a spell! We all know how Luke's face-off against Vader and Palpatine went down. He surrendered himself and focused all of his attention on his father- showing no fear and an outpouring of compassion for him. Vader was torn between warring emotions... and while he tried to remain firmly rooted in the Dark Side and its associated subservience to the Emperor... once the Emperor's attention focused on his only son, a son who had just stood on the brink of the Dark Side and had safely stepped away... he saved his son and threw his master to his death.
Our infinities scenario picks up similarly. Luke surrenders himself to an Imperial patrol. But, to his disappointment, Vader is no where to be found. Instead, he faces the Emperor alone. What happens next?