Ben Solo was born to Princess Leia Organa and Han Solo as their only child. His uncle, Luke Skywalker grew suspicious of Ben's reliance on the dark side. Ben became a Knight of Ren and protector of the First Order's Supreme Leader Snoke. For the next few decades, he has been attacking Resistance bases and wanted to know where Skywalker is. Snoke gave Kylo the task of killing Han Solo at Starkiller Base, an upgrade to the Death Star. Kylo was successful in killing his father, at the cost of the destruction of the Starkiller.
Snoke had penetrated Kylo and Rey's minds as a means of communicating with each other telepathically. At the headquarters of the First Order, Snoke ordered Kylo to finish off the scavenger. However, Kylo killed Snoke with Rey's lightsaber and accused Rey of killing the Supreme Leader. As a result, Kylo Ren became the second Supreme Leader of the First Order. He and his army plotted an assault on the Resistance planet Crait, where he saw a Force projection of his uncle. Kylo attacked the image of his uncle, without knowing it was an image of Luke. Kylo Ren believed that he shattered hopes for the Republic and the Resistance but the worst is yet to come.