Author's Note: I've had the idea for this for a bit and feel like I might as well introduce it before the summer's end. I, like many people, was not satisfied with the final episode of Teen Titans, Things Change. There has to be more to the story, and what better way to continue it than by introducing someone who could have the answers. Not sure how often I'll update, but I will try.

Disclaimer: Any and all rights relating to Doctor Who belong to the BBC and its affiliates. Any and all rights relating to Teen Titans belong to DC Comics and its affiliates.

Prologue: The Mysterious Men

Time stopped still for Garfield Mark Logan during those seconds when his life would change forever. For the young boy, it was his worst nightmare come true: his family was about to face death and he was powerless to stop it from happening. And yet, he felt that he could have done something, anything,to save them. Right now, it was long after that time had passed, but he was still reliving it in his mind, feeling desolate and empty. What would happen now? Where would he go? How could he continue?

A sharp voice soon broke the boy out of his stupor. "Oi! What are you moping around for?" He turned his head towards the direction where the voice came from. When he did, he saw a man possessing a strangely dark aura about him. He was wearing a leather jacket. His hair was cut very short, but what most struck Garfield were his eyes. Those eyes looked like they had seen the horrors of an unimaginable war.

The boy looked down again, unwilling to talk to the stranger. However, it seemed that the stranger wanted to persist. "Oi! I asked you a question. Care to answer?"

He sadly turned at the stranger. "Why do you care?" he glumly questioned.

The man seemed to be a bit taken aback. "Fine! I'll just leave you to mope! See if I care!" The man turned and walked away towards wherever he had come from. The boy thought he had peace for a moment to let his feelings go again, but the man quickly came back. "Alright, do you want to know why I care?"

When the boy didn't respond, the man continued to talk. "I can see it in your eyes. The pain and shock of the first death you've witnessed."

The boy's eyes widened. Was it really that easy to tell? he thought.

The man continued, talking more about himself than the boy. "I don't know why I should anymore, after everything that has happened in my life. The things that I've seen are things that your puny mind can't even begin to imagine. I've seen the horror and agony of billions of lives lost, each one more painful than the last. I guess that's what I do a lot. I bring death, and I have to live with that every day for the rest of my life."

The boy looked into the stranger's eyes again and saw the hues of pain and regret, knowing for sure that the stranger had experienced something that was definitely far worse than what he himself had experienced.

The man maintained eye contact. "But you, Garfield Mark Logan, I presume, don't have to live with that. The lives that I lost were directly my fault. I am a terrible murderer, but you are not. You have a lot to look forward to, so quit moping around. I doubt that's what they would want."

At that point, the man stood up. "I think it's time I take my leave. Remember the words I've said because I won't be repeating them. Be yourself. Be amazing. Because, Garfield Mark Logan, I think you have the potential to be fantastic." Garfield noticed the man smile for the first time. "Off I go then. And so should you."

The boy looked away for a moment, processing everything that the man had just said. "Hang on, mister. I didn't get your name. Who are you?"

The man stopped for a moment. "Not that it matters since I probably won't ever see you again, but…I'm the Doctor."

When he turned around to ask another question, he saw that the man had simply vanished. He didn't know who the stranger was, but he knew that those words held a lot of truth to them. His family would not have wanted him to stop living life. They would, however, have wanted him to become the best person he could be. This lesson he took to heart, and he hoped to one day find that man again and thank him for the wisdom.

"Terra," the same boy whispered years later, "I'm sorry."

The boy, now known as Beast Boy, stared at the large statue of a girl in front of him. At least, it was only a statue upon first glance. He was one of the few who knew the truth that the statue had as recently as a few days ago been a living human being. Her real name was Tara Markov, but everyone knew her as Terra. To the young hero, she was the most amazing person he had ever met. The time they had spent together, whether it was spent on defeating villains with the rest of the Teen Titans or more personal time together, was always incredible. She was the first person he felt he could truly love. With her, the inner desolation from his family's death disappeared, and he could truly feel happy.

Sadly, it had all gone south so quickly. When she betrayed the team's trust and revealed her allegiance to Slade, the Titans' worst enemy, its impact shook them all, none more so than the boy. With her powers, she helped him take over the city, and they were poised to take the world soon after. And yet, he continued to believe in her despite the opinions of his friends. He trusted that she would do the right thing in the end, and she proved him right. She managed to use her powers to kill Slade and end his reign of terror, but she sacrificed herself in the process. Unleashing the full force of her powers transformed her whole body into solid rock. The others comforted him, promising that they would do whatever they could to reverse the process, but he was quickly losing hope that it would ever be possible.

His head was lowered while he muttered silent apologies to her. After a while, though, he realized that someone was patting him on the back in a form of sincere sorrow. Beast Boy turned around and realized that next to him was a strange man. He wore a brown coat and had a blue tie. There was a pair of glasses that he had hanging a bit out of his coat pocket, though he made no move to put them on. Though he felt that he had never seen the man before, there was something in his eyes that seemed familiar.

Voicing his concerns, he spoke up. "Excuse me, who are you?"

The man seemed reproached for a moment, but he afterwards regained his composure. "That's alright then. We've met before, but I can understand why you don't recognize me. You may remember a man with short hair, a leather jacket, and a somewhat rude personality, right? I'm that same man. I've just…had a little work done." He smiled as if he were hiding a secret. "I'm the Doctor."

"Yeah, right. That guy was a completely different person."

"Alright, so what do you want me to do to prove I am who I say I am?"

"Just say something from the time I met the Doctor."

"Very well, then." He cleared his throat before continuing. "Be yourself. Be amazing. Because, Garfield Mark Logan, I think you have the potential to be fantastic."

Beast Boy's eyes lit up in surprise. "You! You're the same man I met when I was a kid! Back when…" He stopped himself, unable to continue the rest of his thoughts. It had been a long time since he had thought back to those days, but the man seemed accepting of his sudden silence.

"It's okay," the Doctor said, "I understand. It wasn't a very good time to chat back then, was it? Neither for me nor you…" He glanced at the statue and stood up. "It seems that it's the same today…" He started walking towards the statue and pulled out a device. It resembled a mechanical pen except that its tip was a blue bulb of some sort. He pressed a button, and the device activated. It glowed and emanated an eerie sound. "Hang on, this isn't a normal rock statue, is it?"

Beast Boy sadly looked up at the man. "Yeah, she's not…"

The Doctor raised his eyebrows in confusion. "She? There's an actual girl in there?"

"She's not in the statue…she…"

"Is the statue," the Doctor finished, putting his device down. He sighed, realizing why Beast Boy was so sad. "She was really close to you, wasn't she?" He nodded while the Doctor continued. "I am sorry…I am so sorry…" Seeing no further reaction from Beast Boy, he continued. "I know I'm rubbish, leaving you here to bear such things when I come, but I need to let you know that things will be okay."

The boy looked up again. "What do you mean?"

The Doctor smiled mysteriously. "We live in a universe where you never know what might happen in the future. Those closest to you often have a knack for showing up when you least expect them. Sometimes, those you lose find ways of coming back. As long as you remember something, it can come back."

Just then, a noise sounded in the background. It was entirely alien to Beast Boy but seemed to be very familiar to the Doctor. "What was that?" the boy asked.

The Doctor gave a look that exuded concern and regret at the same time. "That would be my…means of transport. I really, really have to get going. I'm sorry I couldn't stay long enough to do more or come during better circumstances, but I'm sure we'll meet again. Maybe then, I'll come with an answer to your problems rather than just blather on like the old man I am…"

The Doctor turned to leave, and Beast Boy did likewise. However, he realized that he hadn't thanked the Doctor for breaking his melancholy all those years ago. He turned back, but the man was already gone. Again, Beast Boy felt a sense of confusion, wondering exactly who that man was.