Disclaimer: Of course I don't own Back to the Future or the DeLorean, silly! No matter how much I may want to own the latter. Oh, and no spoilers in the reviews for the second and third films! I've only seen the first one, and that's when this is set, right after the prom scene.

For my own reference, this is my 50th fanfiction (!), and my first one for Back to the Future.

"Marty!" Doc shouted, running in and slapping his protege across the face. "What are you doing? You're setting your parents up with people who aren't each other!"

"That's right, Doc," said Marty serenely. "I'm retroactively sacrificing my own existence for my parents' happiness."

"Marty, that's insane!" Doc exclaimed, shaking his shoulders. "I can't let you do that! I won't! There's not just yourself to think of. What about your brother and sister?"

Marty shrugged. "My parents will marry other people and have kids who'll grow up in happy families. And those kids will owe their existence to me. As for me, I'll never know what I'm missing." He stuffed his hands in his pockets and swallowed. "Doc, my parents clearly weren't made for each other. They made a mistake getting married." And he would have continued, but Doc interrupted him.

"You, a mistake? Why, you're the best mistake that ever happened, Marty! I don't know what I would have done without you! You inspired me to invent time travel! You- "

"Doc, please," said Marty, pushing him aside. "I've made up my mind. This is my decision, not yours."

"You fool!" Doc shouted, slapping Marty again. "Do you realize what you've done? You've created a paradox!"

Marty just stared at him. "A what?"

"A paradox! If you set your parents up with other people, they won't get married, and you cease to exist. But if you don't exist, you can't travel back in time to set them up with other people, and so your parents will inevitably get married and have you! But that means- "

Marty's eyes widened. "So that's why I'm not fading away like my photo?"

"Precisely! You can't continue to exist, but you can't cease to exist either. You've locked yourself into the 'Schrödinger's Cat' dilemma, where you must simultaneously exist and not exist for all eternity! It's like that old riddle where you're passing by the gallows, and the hangman asks you why you came. And you tell him you came there for him to hang you, and since you're neither lying nor telling the truth, he can neither hang you nor let you go. So you're suspended in a sort of limbo, being unable to leave- "

"So what happens to you, Doc? Didn't you anticipate this sort of problem when you invented the flux capacitor?"

"The question you should be asking, Marty, is what happens to you? Your body continues to exist on the time-space continuum, but your presence is no longer detectable to other bodies along said continuum besides myself. You are merely an observer, free to move about as you please, but unable to further affect events."

"So I'm like a ghost?"

"Precisely! Except you're not dead, because you were never alive to begin with."

Marty gulped. "Is there any way to reverse this?"

"I don't know! This is the first time anything like this has ever happened. Literally. I'll see what I can figure out, but frankly, it doesn't look too good for you, Marty McFly. Unless I hurry and set your parents back up together again. But I doubt they'd listen to a crazy old man like me, so I'll have to be crafty- "

"Forget it, Doc. This is for the best." Marty waved his hand dismissively and walked away.

"Marty, wait! Come back! Haven't you ever heard of something called divorce?"

"My parents couldn't get divorced, Doc," said Marty, not turning around. "They can't afford it. Besides, they're waiting for me to turn eighteen and move out of the house."

"But that's not your fault! And what if they could afford it?" Doc caught up with Marty and grabbed him by the shoulders. "Listen, Marty," he said, looking into the boy's eyes. "Your parents love you very much. I'm going to go make sure they get together, causing you to return to your existence in a more... permanent way. Then we'll travel together to 1970, two years after your birth, and I'll persuade your parents to get divorced! Problem solved! How does that sound?"

"No rush, Doc. Not everyone marries their high school sweetheart, you know."

Doc's eyebrows shot up. "Great Scott!" he exclaimed. "You're right! Now, I don't know much about romance, Marty, but I do believe that when people get married at a very young age, the marriages don't tend to work out as well! Perhaps all your parents need is a little time away from each other to, well, grow up!"

"That sounds like a great idea, Doc," said Marty with a smile. "I think it'd be good for them to get out of this tiny town for a while, too."

Doc put his hand on Marty's shoulder. "You know, Marty," he said slowly, "the first time I met you, I thought you were a selfish little brat. But now I can see that that couldn't be farther from the truth. You are the most selfless person I've ever met, and believe me, that's saying something. I've been around the block and met a lot of people. The fact that you keep trying to warn me about this- whatever it is- no matter how much I tell you not to- that shows the great person you truly are. Stubborn as hell, but great."

Marty blushed. "Uh, thanks, Doc," he said, scratching the back of his neck. He didn't have the heart to tell Doc that he was severely overestimating him.

"And I won't stand by while you throw your existence away. For one thing, you're by far the best time-travel companion I've ever had, and the only one I trust besides myself to operate the DeLorean. You must continue to be an active agent in the universe, Marty, for the sake of science and humanity. You mustn't let your knowledge and experience get lost in the folds of the fabric of space-time. Now, people may tell you you're just an average kid, but I know for a fact that that isn't true. And do you want to know how I know?"

Marty folded his arms. "How, Doc?"

"Because you know me!" He slapped Marty hard on the shoulder. "Would I have taken you under my wing if you weren't brilliant? Come on, you stay here. I'm going to go fix this thing with your parents."

Marty rolled his eyes as Doc bolted away across the dance floor. He had no idea what Doc's plan was, or if he even had a plan, and he doubted it would work. He figured he'd find out soon enough. Only time would tell.

A/N: I know this seems like I'm leaving it open for another chapter, but I'm all out of ideas :( Anyway, hope you enjoyed!