Title: Change the World
Spoilers/Timeline: Everything starting from season 2, episode 15; Jacksonville/After season 2, episode 19; The Man From The Other Side. Peter is gone, but still Over Here.
A/N: I can't remember how I came up with this idea, but I loved it! And so I made this story out of it!
Summary: Olivia gets the chance to go back in time and change the future. Will she choose for the sake of the world or her own?

Remember, children, I own nothing!

You could call it an experiment gone wrong or a mistake. Or maybe, just maybe, you could call it an opportunity. Actually, what happened that night was all of above said things. It was an experiment that had gone horribly wrong, it was one of the biggest mistakes they all ever made, but as Olivia found herself in 1985 it also was an opportunity.

She opened her eyes as she lay in the cold snow. She looked around once and it was immediately obvious to her where she was; Lake Reiden.
How ironic, she thought. Of all places, her journey, her mission to undo what happened 25 years ago, began here, where it all started once.
She stood up, whipping the snow of her coat and pants. She had no idea what day it was, she wasn't sure if Walter would come tonight or tomorrow. But if Walter's calculations were right, and she prayed they were, he would come tomorrow. That would give her exactly – she checked her watch – 23 hours. She took a deep breath and then started walking across the lake. She had no idea where she was going, where she would stay the night or, and this was most important, how she would be able to do what she had to do. As she walked towards the road she played every possible scenario in her head. Maybe she should go to Harvard, tell Walternate what he had to do and be done with it. But the man was just like Walter, so he would become awfully suspicious. Wouldn't work.
Maybe she should stop Walter tomorrow night and tell him what kind of trouble he would bring to himself, his family and the world. No, she thought, that wouldn't work either.
Maybe… She wanted to come up with a third plan, but she knew it wouldn't be of any use. Maybe she should sleep on it and see where tomorrow would take her. And as she agreed with her own plan, the insanity of it all hit her. She had just successfully traveled 25 years in time and jumped between universes all in once, and she was still alive.
What started out as a desperate idea with a possibility just became reality. And why? Why was she here tonight? In the coming day and night she would try her best to change the future. Her future. And for the first time this night she began to doubt. For the first time this night she wondered what the hell she was doing. She wanted to run back to where she just woke up, she wanted to go back home, she wanted to just find Peter, and not find a way to prevent him from ever going to her Universe, so he would never leave. So I would never meet him. And as that thought crossed her mind she shook her head. She willed herself to think straight, find a place to sleep and come up with a plan tomorrow. She had made a promise to Walter, again. She would undo what he had started 25 years ago. She would keep the young Peter in his own Universe, and then go back to her Universe and wake up, her life completely different. That was what she would do.
She knew she would stumble across her first problem that very night. As she entered a shady hotel, which she knew would become a nice restaurant twenty years later, well, in her universe that was. As she entered said hotel she knew the reception guy would be slightly suspicious of her money, she knew their coins were different, bur she hoped he would let it pass as foreign money – which it in some way was – and take it, in his need of as least some money. She searched her wallet for the nine dollars, which wasn't that easy since she could only give him 1985 or older coins – she didn't want to dare giving him bills. She managed to find ten dollars and gave it to the man, who had his hand outstretched. When she had placed the money in his hand he looked at it for a little while, shrugged his shoulders and turned around, Olivia silently sighed out of relief. The man turned back a minute later with a dollar in his right hand and a key in his left.
"Keep." She said in a faked accent, accepting only the key. As much as she would love to have the coin, she knew it would came back to bite her in the ass someday. She walked the stairs towards her room, 610, as the man muttered a "thank you."
She opened the door to her room and at the sight of it she promised herself she would make Walter pay for the fact that she had to spend the night there, if she would ever get to see Walter again.
Shaking every thought that made her sad or scared of her mind, she installed herself on the bed, not changing into her pajamas, she hadn't even brought one, and she fell asleep the minute she closed her eyes.
She woke up in the middle of the night; she usually did. She looked around and it took her a minute to realize exactly where she was. As she recited the events of this night in her head, she got an idea. Making sure she wouldn't forget it, she searched for her pen and notebook in her coat, which was hanging over a chair. She quickly scribbled something in the notebook and then returned to the bed. She instantly fell asleep. The dream she engaged herself in would definitely not make it to her top 10 favorites.
As she waited for Peter to open the door she played with her fingers, safely tucked away in her pockets. He opened the door and instantly saw it; he glimmered. Olivia knew very well what happened that night, but her dream, didn't allow it to be like that. As she told him she saw, how he glimmered, he started to disappear. Slowly, piece by piece, until he was completely gone and she found herself in her old house in Jacksonville, rather than his hallway. And as her stepfather entered her room, she jumped away, faint light shining through the window, welcoming her to a new day.