As to Darth Vader, no, when he was Anakin Skywalker he was just a child, an innocent child who's lost too much at certain point. A child born into slavery basically, so he knew how bad it would get. Then the Emperor was slowly spinning his web of dark seduction to him, Emperor was the one responsible for the visions Anakin got of his mother in peril, and he acted out on that, what was the first strand towards falling into the clutches of the dark side. Then he got visions about Padme dying, but what he didn't realize was that he'd be the one who was responsible for that. She, quite poetically, died of heartbreak, she refused to live beyond giving birth to her children. When Anakin was the Darth Vader, he was truly evil, but meeting his son and stopping the Emperor from killing his last link to Amidala, was born out of love, which made him swap again from evil to good. Mind you, when he was evil, he thought he had lost everything, since the Emperor lied to him the entire time. So, basically, yes and no. Anakin has been both good and evil throughout his life. Just as any person is capable of both. Also, as you might've guessed - I love redemption stories.
Edit: Broken freaking quotes lol.
A very long way to prove my point - it's more complicated than simply putting characters into categories
