After watching the Darth Vader Rogue One Rebel Massacre scene at LEAST 45 times, my inner child felt compelled to revisit the mystery of Rey's Vision from the Force Awakens.
What is important to note, is that I've watched every YouTube video made about the vision, and I thoroughly enjoyed all of the hard work and collaborative effort put forth. Without watching these videos, I doubt my interpretation would be as thorough.
Episode 7 is titled the Force Awakens, which is exactly what happens when Rey touches the Skywalker legacy lightsaber. And even though Rey is seen throughout the vision as a bystander, it appears to me that the vision is actually about the Skywalker heirloom. The journey of the Saber, and the events along the way, is what the vision truly reveals.
The opening scene of Cloud City is not only where the Saber was lost, but also where Luke learned the truth of his lineage. As the scene fades we hear Luke scream in mental anguish, and then see him consoling R2 D2 after a massacre of presumably the new Jedi Academy. As the massacre scene shifts from fire to rain, we see Kylo Ren kill one of his own followers. It is easy to remain fixated on the numerous dead bodies surrounding Kylo Ren and his followers , but behind him a flash of lightning reveals a castle in the background. The same flash of lightning also reveals the Skywalker legacy lightsaber in Kylo Ren's possession. These images lead me to believe that Kylo Ren found the saber or stole it, and that the person Kylo Ren saves by killing his own follower, may be Rey's father. The next scene shows Rey on Jakku as a little girl crying out to a ship that appears to be flying into a red Sith looking rectangle. This i believe is about Rey's mother. Rey's mother hides her on Jakku, and was later tortured and killed by Kylo Ren in his quest to find Rey. The final scene of the vision , is one of the future, where Rey ultimately uses the Legacy lightsaber in her duel with Kylo Ren.
In hearing Yoda and Obi-Wan at various times throughout the vision, it made sense to me that in addition to awakening the Force within her, a warning about the dark side of the force was also included. And if you think about what could turn Rey to the dark side, finding out that Kylo Ren killed her family is a very good reason. I do believe that Kylo Ren killed Rey's parents, and I do believe that he knows of Rey through them. I also believe that Han Solo and Leia know who Rey's parents are and what happened to them, as made evident when Maz Kanata asked Han Solo "who's the girl". Because Rey was hidden in a manner eerily similar to Luke and Leia, i choose to believe that her true back story coupled with the death of her family by Kylo Ren, is the tipping point to the dark side. Can't wait to see Episode 8, and the details for Rey in December 2017. May the Force be with you.