What would happen if Finn could grow older and get married to Princess Bubblegum. Would he and PB get to go back into their early to late teenage years (13-17). Disclaimer: I don't own Adventure time.

Story theme: Finn is thinking about growing older. PB is in love. Finn gets an offer.

Finn's POV: I may be able to grow older. But how? Would I miss doing things that I do now. I mean, fighting evil people, playing video games, looking for adventure. Would it be worth it to turn 18. I would be able to propose to PB. My cheeks start flushing with embarrassment. I talked to Jake, who is now married. ''Jake, should I try to find a way to grow older?"
"I don't know. Why do you want to grow older?"
"I want to marry PB." He looked so shocked that he was speechless for a few seconds.
"I can't tell you that. I know I was married because the minimum age for human/candy people is 18. A dog's is lower. I would guess, if you were desperate enough, then ya." Well I decided that I would go for a walk and go clear my mind. As I walked, I ran into this other human. I guessed that we weren't the only left of our species. He had a strange item with him. ''Excuse me sir, but what is that device you got with you?"
"It's an age machine, I just recently created it using the possible sciences here. I need to test it on a few objects before it can officially be used by candy people or us for that matter." That actually amazed me.
"When it can officially be used, I would like to use it."
"Why?" There was a ton of shock in his voice.
"I want to marry the candy person, Princess Bubblegum."
''I know her. She's the one who helped my research the science possible. She said something about someone wanting to turn older. Now I know who it was. I'm Bill."
"Finn." We shook hands then went to the clubhouse. There I grabbed a young tree, a apple, and a banana. His machine made the young tree and old tree, the apple to a rotted apple, the banana to an rotting banana. Then we changed them back the way they were at first: a young tree, a apple,and a banana. He has a dial, so he controls how old people get. He is going to present it at the science thing that PB hosts. We work on a few items on it.

At the Science Fair: PB welcomes all the scientist to her Science Fair. All the other scientist go then Bill is up. I am his assistant. He starts off, ''It is a pleasure to show you all my project. First off, I am Dr. Smith, P.H.D. I am pleased to show the most advanced project of them all." Then he pulls off the cover. "I present to you, the Age Machine. It can change anything/anyone older or younger. I will demonstrate." He has me put a few fruits in it. He puts it in the older mode. They looked rotten. Then he returned them to their original age. He then made me older and then back to my original Then he said, ''Does anybody have questions?" One person asked,
"Will this be available for the public?"
"No, I am making one more for a friend. After that, These won't be made." Then the fair separated. I talked to Bill. "So, could you change my age to eight-teen? I was considering growing older, now I am willing to give up the things I like to do in the age thirteen." He agreed. Then he had me go into the Age machine. He sets the dial to 18 years old. Then I came out taller, and more muscular. Way more muscular. I have a six pack. I am smarter. Bill takes his invention, and heads over to his lab. I head on over to the Palace.

Princess Bubblegum's POV: I was resting thinking about Finn. And speak of the devil, Finn appears only taller, very muscular, and handsomer. He says, "PB, will you go on a date?" I said,
"I never thought you would ask. Yes, I would love to."

Fast forward a couple of months: Me and Finn have gone on a few dates. He suddenly came over, looking very nervous. He gets down on one knee and says, "Princess Bubblegum, you are the love of my life, I want you in my life forever. So, before some prince of another person asks you; will you marry me?" I knew I was blushing. As a matter of fact, I was hoping he would propose to me. So I said, "Finn, I will marry you. For I love you also. It took me a while to find that I loved someone."

After the wedding (Finn's POV): After we are pronounced husband and wife, we kiss. At the reception, I see Bill with his wife. I never knew he had a wife. He comes over to PB and me and said, "Your wedding gift is in the lab. Either tonight or tomorrow you can grab it. I would like you to me my wife, Hillary." We shook hands. After the reception, me and PB go over to the lab to go grab our wedding gift. Bill and Hillary were waiting for us. They opened the grange and showed us the Age Machine. ''I knew you two were in love, so Hillary and I made you two a age machine, so that way you both can turn into 13 year olds again a play pranks. Then when you are done, you can change back into your current ages. Keep it in the palace, away from the public, otherwise, they will seek to use it."
"Thanks for the gift." On the car ride back to the palace I said, "My queen, this age machine will come in handy."
"Finn, please call me Bubblegum. Formalities shouldn't exist between us when we aren't in public. I want to go over to the tree house tomorrow and have some fun."

So what did you think? Happy ending isn't it? I felt that I needed to make this story.