Star Wars has hinted that Luke lied to Han and Leia about why their son fell to the dark side. The Solo-Skywalker family has been beset by tragedy, and to Han and Leia's heartbreak their son Ben Solo became Kylo Ren, apprentice to Supreme Leader Snoke and now the man in charge of the First Order.
Kylo Ren's fall to the dark side seems to have begun as a result of his fascination with his grandfather, Darth Vader. But Star Wars: The Last Jedi revealed that the turning point came when his uncle, Luke Skywalker, sensed the darkness growing within him. There was an instant of impulse in which Luke ignited his lightsaber over his sleeping nephew; the Jedi Master realized he was wrong, but too late, as Ben awoke and defended himself, turning away from the Jedi once and for all. Luke was never able to forgive himself for this momentary lapse in judgment.
Making matters even worse, the latest Star Wars novel - Rebecca Roanhorse's Resistance Reborn - hints that Luke may never have told Leia the truth of that terrible day. In one early scene, Rey and Leia discuss Kylo Ren. Rey is still conflicted after the events of Star Wars: The Last Jedi, and she approaches Leia for answers.
"Kylo Ren. He's your son..."
Ah. Leia nodded and drank from her now cooling cup. Rey squirmed uncomfortably in her seat.
"What happened to him?" she finally asked. "I mean, how did he turn to the dark side? He started in the light, didn't he? He told me a story about Luke, about his training." She exhaled. "I guess I just want to understand."
"I do, too."
"So you don't know?"
"I think you would have to ask Ben what happened to him."
"He wanted me to join him, but I couldn't. I thought I could help him, but he only wanted me to become like him."
Rey's face fell, and Leia could see the pain etched there. The girl cared about Ben, and he had disappointed her. "Ben has made his choices," Leia said. "No one can save Ben but himself. And I don't know if that is what he wants."
It's an intriguing scene, not least because Roanhorse carefully avoids giving a sense of Leia's emotions. A surface reading, however, strongly suggests that Leia has never been told the truth about how Ben Solo became Kylo Ren. It's even possible that Luke exiled himself to Ahch-To before speaking to his sister, consumed by guilt over what he had done. If that's the case, poor Leia has nothing but unanswered questions. At the same time, though, it's interesting to note that she doesn't ask Rey to tell her what Kylo Ren said about Luke. It's possible that Leia's grief is still too raw, and she doesn't want to think badly of Luke just a few days after he has sacrificed himself. Alternatively, it could well be that she doesn't trust anything her son has said, figuring it was just to manipulate Rey.
This shines a disturbing light on Han Solo's tragic death in Star Wars: The Force Awakens, because it suggests that Han and Leia had no idea what had happened to their son, and were instead blindly trusting that he be could be redeemed. They didn't know why Ben had fallen to the dark side, why he had become part of the First Order, and as a result they had no real understanding of how Kylo Ren could be brought back to the light side. As a result, Han walked into the situation on Starkiller Base and took a shot at redeeming his son when he had no real sense of where the target was.