Ben Solo — Kylo Ren — is a human male, son of Han Solo and Leia Organa and nephew of Luke Skywalker. He was introduced in Star Wars: Episode VII The Force Awakens (2015) and played by Adam Driver.
Not a Vader clone
The obvious reading is that he is the trilogy's Vader. The films argue the opposite: Vader was calm and Kylo is not, Vader concealed his conflict and Kylo cannot, and the mask is a costume rather than life support. He is a young man performing an inherited villainy he does not have the temperament for, and the story knows it.
What the books add
Canon fiction has filled in the fall in pieces — the Jedi temple, the night Luke considered killing him, the Knights of Ren, the manipulation by Snoke and behind Snoke by Palpatine. Charles Soule's The Rise of Kylo Ren comic series is the most direct account, and it makes the moment of no return smaller and more plausible than either film manages.
The Legends counterpart
Legends did a version of this story first, and much longer: Jacen Solo, Han and Leia's son, falls to the dark side over the nine-book Legacy of the Force series. Readers often compare the two. Jacen's fall is slower, better argued and considerably more damning; Ben's is faster and more emotionally legible. They are not the same character and neither is a draft of the other.
Reading note
Read Bloodline before the sequel-era material. Knowing what the galaxy learns about Leia's parentage, and when, changes how you read everything that happens to her son.
