"Search your feelings, Father. You can't do this. I feel the conflict within you. Let go of your hate,"
Anakin had loved four people. Four people he would have given his life for. And Darth Vader had learned from his predecessor's mistakes.
The first was his mother. She was the one who reminded Anakin that he was a he not an it, a boy not a droid, a man not a machine. She showed him it was possible to be happy under the hardest of conditions. It was natural that he loved her first because she was the first to love him. He had left her in slavery for the Jedi when he was nine years old. When he later begged to return to her (just the check on her, no more, he swore), his master refused again and again. For three months he watched her tortured every night. Vader, though he was not yet named, was born the night she died and celebrated by killing all in his path while Anakin mourned and loved her. Shmi died in Anakin's arms.
He had so many memories of her smiling, but they had faded away into the sand leaving him with blood and screams to honor her by.
The second was his emperor. When Anakin had arrived on Coruscant the second time with his new master it was hard for him. He had left his mother on Tatooine and his Padme on Naboo and lost the only other person who put any value on him to death. His new master didn't want him in the first place, the council made their feelings on the subject very clear. But Palpatine, the most powerful man in the Republic, took time to sit down and do nothing but talk to a former slave about everything and nothing. He supported and encouraged Anakin, becoming a sort of father figure. It was all a lie of course, a way to get the Chosen One. He knew this and as Vader knelt before the man to receive his power and name, Anakin mourned and loved him. Palpatine manipulated Anakin's emotions.
He was a slave again, this time to a far crueler master. He had no delusions left as the lightening ripped across his back.
The third was his master. Obi-Wan was like a brother to him. Anakin saved the man many times and would not have hunted him down, even if Kenobi was a Jedi. But Obi-Wan had sought to use Padme against him. His master betrayed him at the order of Yoda just because Yoda was an older Jedi. Not because the two had fought together, survived together, nearly died together. Not because Yoda would have mourned him or risked everything for him. Obi-Wan betrayed him, using first Padme, then Luke, and topping it all off by leaving him to a cruel death on Mustafar. Yet even when Vader took savage pleasure in striking him down in hatred, Anakin mourned and loved him. Obi-Wan betrayed Anakin's trust.
A scholar once said that love was giving someone the ability to destroy you and trusting them not to. Anakin agreed – he knew what it was like to be destroyed.
The last was his wife. In life and death alike she had ruled his heart and now haunted his every waking moment. But night was the worst. At night he felt her blood on his hands although she had never bled. At night he saw every death he caused, every crime he committed happen to her. She called out for him to save her even as he killed her. But he could not stop, could never stop. He saw himself torture her, heard her screams. But only after, when she lay on the rack like a broken doll, did he regain control of his body. Then he could rush up to her, free her, hold her, brush her hair back and apologize many times over. But she would never respond and the next time Vader dreamed it would be the same. He would remember his victims that day – the ones who had desperately clawed for air, the ones that died under a blood-red blade, the ones that stood before the stromtroopers to be shot – and they would become her. A constant reminder of her murder. Vader would awaken screaming, cursing Obi-Wan a thousand times over, and Anakin screamed with him as he mourned and loved her. Padme died by Anakin's hand.
Her death hurt worst of all.
After he learned of her death that terrible day Vader had sworn not to love again. And he wouldn't. All those he loved he lost: his mother and wife to death, his brother and father to betrayal. He stood looking upon his humble, gentle mother's last descendant, his steady, traitorous brother's last betrayal, his sly, treacherous father's new apprentice, and his beautiful, innocent wife's last gift to the unworthy and wondered how in the Force he could explain all this to his son.
How could he tell this to the child with bright eyes alive with hope tempered only by his little knowledge of the difficult path? Could he explain that what he offered above Bespin was all he had? Power he had promised, a chance for them to be together. These things he had, these things Vader could give his son. But love? Love lifted you into Heaven to body-slam you into Hell. He had loved too much, was too broken to try again. He hadn't survived the death of the boy's mother, not really.
Last time he and Luke had met Luke had thrown himself to his death rather than acknowledge their relationship. He had hoped before that he might perhaps allow himself to care for his offspring. But Vader was glad he had not dared. It didn't hurt as much as Mustafar.
Vader blocked the name out of his mind and brought himself back to the present issue. How to explain to Luke his pervious experiences? How to tell the boy that after the rejection at Bespin Luke just showing up was going to make him suspicious, even more wary if that was possible? How to tell his son he would not love him?
Let go of your hate… but hate was his shield against love. It would be better if the boy hated him. Though he knew the pain would be great he understood hate. He drew it close to him, wrapped it around what was left of his shattered heart to create an armor stronger than any other he wore. Hate was straightforward. It was powerful and all consuming, leaving no room for hesitation and doubts. It attacked when threatened, destroyed when tested, and required nothing. Love forgave when threatened, preserved when tested, and required you to be utterly vulnerable. It was complicated, needed work and upkeep. It involved other emotions like grief, loss, and pain. And his son wanted this from him? This frightening emotion?
When Darth Maul's doppelganger had challenged Vader Sidious' once-apprentice asked, "What could you hate enough to destroy me?" Vader's answer had been simple then, "Myself."
And now Luke was asking a different, more complicated, question, "Who do you love enough to save me?" Vader's answer should have been, "No one."
Vader turned to address his son and realized that there was no question. Just love, unconditional. Love he would not return. But how to tell Luke? How could he explain his past well enough that the boy would understand that his father was incapable of loving him, incapable of saving him? He couldn't, not really, because he supposed some part of him didn't believe it. But he couldn't just ignore what Luke said, couldn't send his son before the Emperor with false expectations of a father's love. His past experiences with love could not be brushed aside and forgotten. He could have loved the boy once, did love the boy once. When Anakin and Padme had been curled up on the couch together deciding names or that first day when Anakin had learned… but he was not Anakin, not any more and it was far too late now, too much had happened. But how to say this to one who could love? Who could love one such as him? What could he possibly say?
"It is too late for me, son."