A/N: Mostly canon compilant until shortly after the Battle of Hogwarts. Afterwards, well, go and see for yourself.
Disclaimer: Nothing mine, beside Death. Well, my version of him anyway.
Edited: 22/11/2020
Chapter 1
Harry James Potter, saviour of the wizarding world, Conqueror of the Dark Lord, stared at the entity blankly. The entity stared back. A confusing concept, seeing as it did not have any eyes.
In the silence that stretched between them, the whimpering from the bundle in Harry's arms sounded even louder.
"Harry James Potter," the voice came from all around him instead of from the entity itself.
"Death," Harry acknowledged with a soft sigh.
"You have been here for a long time." There was a pause. "Or at least it would have felt like a long time to you. Time is of no consequence in this plane."
Instead of answering Harry let his eyes wander over the entity's shoulder. Behind it stood the Hogwarts express. The conversation with Dumbledore was still fresh in his mind, even though he felt like it happened a very long time ago.
After the Battle of Hogwarts, as the people called it nowadays, Harry had felt numb. The war was over. The Dark Lord had been defeated and the Death Eaters scattered. Yet so many had died to accomplish that. Lavender Brown, Colin, Fred... Even now, Harry's heart twinged when he thought about them. There would never again be a Fred to the George. George had still been unresponsive when Harry had last seen him.
Then there were Tonks and Remus. Remus had promised to come back. Back to his little son, who needed him. Andromeda had been unconsolable, clutching Teddy tightly to her chest when she found out.
Dobby….his death had hit him hard. He had started to rely on the crazy house elve without even noticing until he was gone. Dobby had died without truly understanding how thankful Harry was about him.
Cedric…
Sirius… The only father figure he had ever known, the only-
Harry shook his head and forced his thoughts back on track. After the Battle of Hogwarts he had been a shell of himself. He had been so lost in grief and mourning that nothing truly mattered to him. Hermione and Ron had tried to help. They truly had, but Ron had been mourning family members himself and Hermione had been beside herself with worry about her parents. It had not helped that every time he looked at Ron he had seen Fred's corpse and George's grief-stricken face.
Days, weeks and then months had passed before the wizarding world, while vastly diminished, had slowly begun to recover. The remaining members of the Weasley family and Harry had made memorial stones for those lost.
They had given each of their friends and loved ones the funeral they deserved. While it had started out with only them, soon more and more people had come to say their own quiet goodbyes.
Harry even once saw Narcissa Malfoy kneeling in the grass in front of Sirius and Tonks graves. It had shocked him to the core and it had taken him embarrassingly long to realise that she had lost more than most in this war. Bellatrix had been her sister, Lucius was her husband and Draco her son, yes, but Sirius had been her cousin and Tonks her niece.
It was then and there that he had decided to help her with Draco's trial. It had been the right thing to do anyway and she only ever wanted to protect her family. That was something that Harry could respect.
The Death Eater trials were nearly too much for Harry. They happened one after another and each and every time Harry was called as witness. No matter if he knew the person accused of being a Death Eater or not. It was simply assumed he did, because he was their saviour and therefore, apparently, all-knowing in the eyes of the wizarding world.
In the end though, Harry had managed to pull through. He had helped serve justice and Sirius would have been proud of him, he was sure of it. So, when he exited the Ministry of Magic after the last trial, smiling for the first time since the war truly began, Harry had not expected to come face to face with a Death Eater. Nor had he had the time to avoid the killing curse racing towards him.
When he awoke in the station of King's Cross station again, he had been confused at first. Then the anger had set in. Ghostly flames had spread from his body as a representation of his anger. The platform had been covered in flames in the blink of an eye. The train had begun to rust and fall apart, the ground shook. His ire had been so great, so filled with grief and desperation and whywhyWHYamIstillnotallowedtodie that he had let his emotions run free.
The destruction of the platform hadn't mattered. It was only a representation of its counterpart in the real world anyway. So, the flames grew brighter and the train fell apart faster and Harry's grasp on reality had begun to slip. He had even lost himself to the anger and anguish for a moment until he had heard a scream. It was a loud, ear-numbing noise. One full of pain and it had made Harry's whole body stiffen as his very being had trembled. He knew that noise.
In a heartbeat the platform had been back to its original state and Harry stared at the ugly baby that lay there on the floor, crying its eyes out. Voldemort's soul. Harry thought it was incredibly ironic that Voldemort was the one who had brought him back from the brim of insanity to which a Death Eater and Voldemort himself had pushed him. Ironic and fitting in a very strange way.
After that Harry had wandered around the platform. There had been no one there. No one beside the Voldemort baby. He entered the Howgwart's express a few times. Went through each compartment in the hopes of finding a clue of why he was here or to travel on, but nothing had happened.
So, for a long time he had waited. He spent the time reflecting on his life, the people that were important to him and to grieve. Truly mourn all of the lost and hope for the happiness and well-being of all of his loved ones who had survived the war.
He had just picked up the Voldemort baby, out of pity and longing for a past that should have been and a future that never was, when the entity appeared.
"You have decided." Harry sharply looked up from where he had been staring at the not-baby in his arms.
"What?"
"It is good you have chosen a path," the entity continued as if it had not heard Harry. "I shall grant your wish."
Before Harry had any chance to reply, he saw the invisibility cloak float over his shoulders mere millimeters away from touching him. In his free hand the elder wand appeared.
Harry stared at Death in bewilderment and slight alarm as one after another the three hallows appeared. The resurrection stone brightly where it floated in front of him in the air.
"How-? When-? What-? Huh?!"
The not-baby went eerily quiet. Harry was too shocked to even consider looking down to see what that meant.
"The Deathly Hallows are united again." The echoing voice was without inflection. "The choice was made. The price was paid. The gift shall be awakened." A warmth spread in Harry's body and he tensed unsure of what it meant. "Magic will guide and Fate shall be your judge." Harry's body began to fade. "We shall meet again, Harry James Potter."
The cloak fully settled around him and the faint sound of a whistle could be heard. The resurrection stone's light blinded him. Harry was forced to squeeze his eyes into narrow slits. He felt the weight in his arms disappear and as he looked down, everything went white.