He thinks how people used to say that a defining feature of Anakin Skywalker was his bravery (some called it recklessness) and his selflessness. People now say (behind closed doors) that a defining feature of Darth Vader is his brutality and his rage.
When he paces up with and down a star destroyer with his black cloak sweeping behind him he cannot help but notice how much the people fear him. He thinks back to the time when Palpatine said it was better to be feared than loved though at times he wishes it was the other way round.
He remembers when he had dreams about Padme, Obi Wan and even Ahsoka but now (even though three months have past) he only has dreams of scorching pain, fire licking at limbs, children that he killed at the Temple asking for his help, Padme with tears coursing down her cheeks and the child Padme never gave birth to.
He never admits they are nightmares but he still tosses and turns and wakes up in a cold sweat every night.
He thinks that Sith are not supposed to experience this, Sith are supposed to be all powerful, Sith are supposed to be able to stop people from dying and yet he does, he isn't and he can't.
He remembers how Obi Wan used to naively say dreams pass in time and he knows for certain these ones never will as they are etched into his mind like the patterns are etched into the japor snippet he gave to Padme.