Star Wars: Rogue One - 10 Ways It Changes A New Hope
8. Darth Vader's Behavior And Musings
Despite his relatively restrained nature in the opening scene, Vader still appears to be very high-strung throughout the duration of the film. He's not going on an absolute rampage like he did at the end of Rogue One, as again, that likely served as a way for him to vent, but he still has absolutely no problem choking a rebel to death with minimal effort.
While it's not always overt, it now very much seems like Vader is running on an adrenaline high after the events of Rogue One. This is apparent by the aforementioned choking of a man to death during an interrogation, his merciless killing of Obi-Wan which was preceded by self-indulgent gloating, and his haste in taking to his fighter to put a stop to the assault on the Death Star himself. Vader is absolutely furious that the Rebel Alliance got the best of him and managed to escape with the plans, and is determined to not let such a defeat befall him again.
In addition, certain quotes and reflections the Sith lord has throughout the film now seem to feel much more at home. Most notably, his line similar to that of C-3PO's, in which he proclaims to an Imperial officer that "There'll be no one to stop us this time." We now know that he was referring to what had just taken place on Scarif.