Ben Solo/Kylo Ren.
As much as Beru Lars remarked about Luke that there was too much of his father in him, there is far more of Vader in his grandson. Luke, when faced with the ultimate choice, powered down his lightsaber and refused to kill his own father. When confronted with the same choice, Ben Solo hesitated for barely a moment before igniting his and making his journey towards the Dark Side complete. He ceased to be the grandson of the Jedi Anakin Skywalker and fully became Kylo Ren.
When he arrived at another crossroads following Snoke’s death, he again chose the dark path, later unleashing his full fury, and the might of the First Order, on (what he thought to be) his uncle. It’s difficult to believe he’ll find redemption in Episode IX.
Yes, there is indeed something sinister about the Skywalkers. Perhaps none of them were meant to bring balance to the Force, and that burden now lies with Rey. We’ll just have to wait and see.