Darth Vader had no father.
It was simple enough of a premise, though many would undoubtedly misinterpret it. Darth Vader's lack of a father was not because of death; for real and true, he would acknowledge to himself, he was the bastard child of no man. Obi-Wan had explained it a long time ago, a lifetime ago; some people were so strong in the Force that it was the Force itself that caused their birth. In that sense, he supposed, the entire galaxy was his father...and, to be honest, he preferred the option of being fatherless. His father was the Force, because he had been destined for greatness.
Whether that greatness had been his service in the Clone Wars, or the destruction of the Jedi, the birth of his children, or something else...that couldn't be determined yet. Luke was strong in the Force, though, and knew his father. It was one of the things that Vader had promised himself before his fall to the Dark Side: any of his children would know who their father was. He wouldn't leave them to wonder, as he so often had before the truth came to him. Their father was a different man than he had once been, but some things would never change. A father's bond with his children was mysterious; he could faintly sense them, no matter where they were, and the feeling was stronger when they came closer. In that sense, he had known Leia was his daughter. He had done his best to avoid telling her, knowing both that she was fairly insensitive to the Force and that she would never believe him if he made it known.
He'd had no qualms about obliterating Alderaan, however. They were not his children, not his family, and so he could embrace his role as the Emperor's right hand. He had felt Leia's pain as if it were his own, and had been forced to take a step back at the grief coursing through her...he despised that he had to make his only daughter go through that. Obi-Wan had come back, then, for a few moments.
He had wanted to tell his former teacher, his once-brother, of so many things. How much he missed Padmé, and hated the Emperor, and even how he still very much wanted to cross lightsabers with Yoda. The ancient man had wanted a battle, however, despite knowing that there would be no repetition of Mustafar. Their words had been exchanged with thrumming blades, parries and blocks, slashes and stabs and counters. Vader had conveyed his sorrow and grief, and Obi-Wan his regret; each of them fought for different things, though they knew what the outcome would be. Obi-Wan Kenobi fought for the same reason he had in the Clone Wars: a new hope, the thought that tomorrow might be just a little better than yesterday. Vader battled for purpose, for duty, for penance. Vader fought in the hope that he would give his children enough time to escape the Death Star. He'd seen his son's face as Obi-Wan had allowed himself to be cut down, vanishing with the Force, and felt again the anguish of having precious people robbed of you.
Darth Vader had felt it doubly, however, because the man had been important to himself as well. In the days of his training, Obi-Wan had been like a father to him...and, as stated before, a father and child have their own strange connection.
Vader's son and daughter had taken after their parents very well, he knew. Luke looked almost exactly like he had when he'd been younger, though perhaps more tanned and with lighter hair. Leia clearly took after her mother, with her brown hair and pale skin and political status...which brought up a topic that the Dark Lord didn't want to think about, lest he be overtaken by his grief.
Darth Vader would not allow himself to be dragged down by his misery. Not even as he approached the Emperor with his son in tow. It had all of his willpower to prevent slaying the guards and escaping with his son, finishing the boy's training in the Force and living to fight and kill Darth Sidious another day...mostly because he knew that he would be able to do it. Palpatine's power with the Force, while mighty with the weight of ages behind it, could not compare to Vader's absolute mastery over the energy of life that ebbed and flowed with the galaxy. He had been molded by his teachers, in place of a father, but had surpassed all of them. Qui-Gon Jinn, Obi-Wan Kenobi, Darth Sidious...he could even say that, as those who came before him, Darth Maul and Darth Tyrannus were his tutors as well. Watto might also be a teacher, showing him the value of work and allowing him to familiarize himself with the knowledge of the machinery that would eventually take over his life and body.
That was a story for another time, however. Darth Vader had to content himself with knowing that his children knew him, as he never could. If there was any regret in the Sith Lord's mind, regarding his son and daughter, it would be that they could never know him as he would have wished to be known: a hero of the Clone Wars, the savior of Naboo, a loving husband and an ultimately protective father.
In his final moments, gazing at Luke without the protection of the mask, Darth Vader has thrown away the darkness of his life. He finds great joy in the knowledge that he will go to join his brethren, though he laments that it will mean leaving his son and daughter behind for the second time in their young lives. His death will bring peace. His return to the light achieves the balance that was so sought-after in a time before the Empire, the age of the Republic and its Jedi Knights. As he hears Padmé's voice one more time, finally allowing her to return to his mind, she sings him to sleep with her lullaby, saved for the nightmares he sometimes woke from. He allows his iron-hard control to slip just once more,a tear rolling down the side of his face.
He is going to be with the ones he loved, but there will be no man among them who is his father. Darth Vader has no father. He is the child of Tatooine, of sun-blasted sand and scorching winds, a slave who gained freedom before falling to the chains of the Empire. He is the son of no man, but born of the Force itself. He is the bastard of rage and fury, hatred and battle.
So why was it, as the Chosen One joined with his father and creator at long last, that he felt like he had come home?