What If Rhaegar Targaryen KILLED Robert Baratheon? | Game of Thrones

We go through how the events of Game of Thrones would change if the Rhaegar Targaryen KILLED Robert Baratheon. What would King Rhaegar's next move be, would there be on trial of his father the Mad King? How would he get Ned Stark on his side after running away with Lyanna Stark? Does Jon Snow come to King's Landing or go with Ned Stark? Does Tywin Lannister come back as the next Hand of the King?