Sorrow.
This was all the Doctor could think of.
"I...I am sorry." he whispered. A tear dropped from his crying face. It should not have ended like this...
It all began when the Doctor landed the TARDIS back at present-day Earth with his companion, Natalie.
The Daleks under the leadership of their dreaded creator Davros, had masterminded a full-scale invasion as vengeance for everything the Doctor has ever done in his previous incarnations. After a long battle of defending the planet, the Doctor with Natalie sneaked past the Daleks`to arrive onto Davros`s mothership.
Although this was all a simple deception. Davros long anticipated he will come, the invasion was only a distraction. With the Doctor weakened after defeating the Dalek Emperor, Davros had finally sealed the last Time Lord on board.
"All of this, Davros." the Doctor looked calmly at his ancient enemy. "What did you want to fulfill, revenge after the fall of Gallifrey?"
"My dear Doctor." Davros responded viciously. "I wanted to watch you despair. From the beginning you are a lonely, corrupt being who has lived an ancient life. After all this time, you should know the universe has no place for a man like you. You will only become a sad memory at the end."
"Oh?" Natalie glared. "A lonely, corrupt being like you?"
Davros silently stared at her. "This is my victory, Doctor. Watch me reveal who you are on the inside. Exterminate the girl."
"Ex-terminate!" The Supreme Dalek aimed at Natalie.
The Doctor quickly countered with his sonic-screwdriver, only it was too late. The screwdriver merely weakened the Dalek-laser, the attack wounding Natalie on her arm. The girl screamed, blood flying everywhere before falling lifelessly unconscious onto the ground.
"Natalie!" the Doctor screamed.
Davros smirked victoriously. "Ah, behold. The madman with a box, the savior of the universe who cannot save a mere girl. You should have not interfered, she would have a quick death. Instead, your kindness brought her unnecessary pain. Death is all you are on the inside. What my glorious benefactor mentioned was true about you."
"Who?" the Doctor blinked. There was someone Davros was allied with? "Who is this benefactor?"
Davros smirked silently. "Oh...it is a little secret. A stranger from the outside. One who is quite knowledgeable about your tragic self. He is behind all that shadows the darkness of creation itself. A mastermind of eternity..."
The Doctor hesitated before quietly picking up a Dalek laser-stick on the ground. "You..." The Fury of the Last Time Lord screamed within, howling for vengeance. All the man`s inner darkness was being released after an eternity. Davros will regret this. All the Daleks will regret this. Silence will fall upon this enemy. Forget about restraining himself, this was the moment to end everything. Forever. This was what he should have done as the incarnation of War itself.
Davros froze when the Doctor himself smirked. "What are you...?"
The Oncoming Storm was unleashed.
The Doctor sighed.
What happened afterwards was only a memory.
He had destroyed the Daleks. All of them who invaded the Earth. Davros himself had ran away in fear of him, the Destroyer of Worlds.
Natalie was brought to the UNIT (Unified Intelligence Taskforce) military hospital in London, with a blood-stained Doctor carrying her. The girl had lost her arm in the battle. A wound that the Doctor himself could never cure from out of regret. All this time he was still a lonely madman, with nothing to look forward to except wandering around the multiverse since the beginning. He had stayed beside the girl as she recovered from the aftermath of the tragic battle.
The day finally came when she awoke.
The Doctor himself was wandering around the hospital, thinking about his past, present, and future in his clever mind. A clever mind that failed to save the girl...
"Doctor?" a weak voice called.
The madman looked up to sight Natalie coming towards him on a wheelchair. "Natalie...I...I`m sorry." I..."
"Doctor...I`m fine." the girl responded sadly. "I know you tried to protect me."
The Doctor was quiet. Although he saved the universe throughout all his previous incarnations, what remained behind was forever sorrow of those he was unable to help. This was one of those moments. "I..."
"I forgive you." Natalie finally smiled. "You are a Doctor, after all."
A Doctor who was unable to save this girl. With his hearts in pain, the madman stood up. He cannot forgive himself for this. The Doctor quickly walked away without look back.
Natalie could only watch the Doctor depart, sorrow in her heart. The madman will never return, it was a promise of what he thought was atonement for himself.
The TARDIS beeped quietly when the man returned, knowing what happened. "What have I become...?" he asked to the old dear. A man whose incarnations had many nicknames, only to be be hopeless where it is needed. Should he ever run away from Gallifrey in the first place? All of creation acknowledges his name, although he was a lonely being with a heart of never-ending inner darkness.
What should he do?
The worst was yet to come. There was someone behind all of this. Only...who was it?
This was a paradox. He was a man of infinite potential, only he cannot save the one closest to him in the end.
With this, the Doctor recognized with dread the end of his life was coming. After all this time wandering around all of creation...
What redemption could he look forward to? He will know no more.
The only greater question than this is his name itself. The unknown question that will never be recognized until the end. The death of his identity throughout the universe for all eternity.
"The answer will never be there for me..." the Doctor sighed.
The TARDIS de-materialized.