This was a Star Wars comic where a Jedi in hiding encounters Vader. One scene I remember is where a ship full of civilians is trying to escape from the Empire. Vader encounters the Jedi and tells him that he will spare the ship and its crew if he turns to the Dark Side. Eventually, the Jedi accepts, only for Vader to activate a bomb planted aboard the ship. The comic ends with him saying that, whatever the fallen Jedi will do from that point on, it will serve the Emperor, and walks away. The Jedi ends up committing suicide with his lightsaber.
This is 'The Duty'
It is the time of the Great Jedi Purge. One Jedi by the name of Gira is the last man standing in defending a group of Padawans from an Imperial attack. As the Padawans make their way safely to an escape ship, Gira dispatches the last of the stormtroopers. His success is cut short when he encounters Darth Vader who forces him towards the dark side. Gira defiantly refuses to give in until the safety of the padawans is jeopardized. However, Vader kills the Padawans anyway, and Gira commits suicide.