Disclaimer: I don't own Adventure Time.

Hey guys! Those who were awaiting Marceline action... you got it! Other than that, I have nothing else to tell you! Read on you shall find out.

This is Chapter 4

"You told me you liked me, and you made my flame grow brighter, but then you put me out, which hurt!" exclaimed Flame Princess, , "Thank you for building my new home, Finn. I'm so happy." replied Flame Princess with gratitude, , "Finn, even if we like each other, we're going to hurt each other…" said Flame Princess. An array of images of Flame Princess were shown. "Bye, Finn." Flame Princess said.

"Give me a hug, hero" demanded 13-year-old PB sweetly, "You so spice!" giggled 13-year-old PB, "Please, I need the real you!" pleaded PB, "You're jealous of Ricardio," said PB knowingly ,"Finn, I feel like a big idiot for doubting you!" guiltily replied PB, "You did that for me?" PB asked flattered. "A whopping love hug is needed to finish the reaction" 13-year-old PB said as she smiled at Finn. Various images of Princess Bubblegum appeared. "Finn, of course I like you" Princess said, swallowing her mouthful of spaghetti.

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Finn woke up in hot sweat. "What a weird dream…." he thought as he removed his hat, running his fingers through his hair. He sat in a daze for about 10 minutes, and then decided to take a shower. "Maybe it'll help." He got in the bathroom and started the water. He let the hot water run until the room filled with steam, flooding his airways with water vapor. He took a deep breath. "Ahhhh, this feels….great" said as he breathed in more steam. Finn was in and out of the shower within 15 minutes. He stared at himself in the mirror. "I look a lot like….my dad. Wow… that's going to take some getting used to saying." he thought as he ran his fingers over his moustache and goatee. He wrapped a towel around his lower half and walked into the larger room.

At this time, someone knocked on his door. "Finn, are you awake? I came to finish the reflex tests and start the others." Princess Bubblegum muffled through the door. "Oh yeah, I'm awake. Let me just get dressed and I'll be out in 5 minutes." Finn replied plainly. At the mention that Finn wasn't dressed yet, PB's breath heightened and she started blushing. She grabbed the doorknob frantically as her knees began to go weak. A naked 19-year-old Finn was just too much, this early. She managed to get a quick alright out to Finn's door before she raced to her lab. She stabled herself on one of the tables, desperately trying to shake the moment of weakness. "Am I even going to be able to survive the next few days, let alone the next month?" she silently asked herself.

A loud bang on the door, startled her, it was then followed by Finn's voice "Hey Princess! Are you in there?". She quickly composed herself and opened the door. PB stared at the now clean, groomed Finn. She gazed at his golden hair which now reached his waist and then looked over his shirt which now was too small and showcased his well-toned chest and stomach muscles.

"Hello Finn." PB replied slightly out of breath. "Why aren't you wearing your hat?" she inquired somewhat confused at this change.

"I don't know, I just don't feel the need to wear it, I guess. Weird, huh?" Finn answered scratching his head.

PB nodded with an inquisitive look on her face "Indeed."

"So what was the next reflex test again? Malmary diving?" questioned Finn.

"No, silly. It is the Mammalian Diving reflex ." PB giggled "We'll have to go outside again for this one. I have had Peppermint Butler already prepare a pool full of cold water for it."

"COLD water? Why?" Finn asked apprehensively.

"Well, a normal reflex for adult humans is the Mammalian Diving reflex. This is where, when an adult human's face comes in contact with cold water, their heart immediately slows its beats per minute and after being in the cold water for a while, blood circulation is cut off from the extremities. From what I understand, this reflex enables humans to stay underwater for extended periods of time." PB responded informatively.

"Oh well, how long will I have to be in the water?" pried Finn.

PB quickly replied "Not too long, just 5 minutes."

Finn nodded and then followed PB. Strangely, she didn't lead them outside. She led them to her room. Finn looked at her questioningly. She quickly replied "Oh well, I have to change my clothes. You see, I have to measure your heart beat, while you're in the water. And I don't plan on ruining any of my dresses. Peppermint Butler will show you to the pool. I will be down shortly." Finn began to follow Peppermint Butler out as PB closed the door behind her.

The sun seemed pretty happy to Finn as he waited for PB to get this test started. "It's so…..warm." he said as he opened his arms to the sunrays that provided him this warmth. "Kinda like… Flame Princess" he sighed as her realized that he had forgotten all about her. "I guess since I didn't see anything go up into flames yesterday, Jake must have completed his mission righteously. That makes me feel better. Hm, at least I won't have to peel off burnt skin for a while." Finn thought as he smiled to himself, remembering all of the times Flame Princess accidently burned him. "She doesn't seem evil except of course when she's mad. Her dad said she is, though….. maybe she's nice when I'm around. I have to be the one to change her….." Finn decided.

When PB finally came down, Finn was at a loss for words, all thoughts of Flame Princess instantly evaporated. She wore a polka-dotted bikini top, some fringed shorts. The outfit was an unsurprising pink, her favorite color, nothing special. Yet, that wasn't what caught Finn's tongue. It was her and all her beauty. She could make any plain, simple outfit look fantastic. He looked away. Admiring her beauty made him remember his crush on her, the fact that he still had one, just not as intense, and the fact that she would never feel the same way. He gritted his teeth; it hurt to remember that. He tried hard to brush the thoughts away and keep what he was feeling off of his face as she approached him.

"You ready?" she asked, pausing to question the flicker of emotion that Finn's eyes had flashed a moment ago. "Hmmm… what was that? Pain? I wonder what he could be thinking about …. Maybe I'm just over-analyzing things. Yeah it was probably nothing" PB thought. Finn nodded. He closed his eyes, waited a few seconds and then jumped into the freezing water. A few moments after, PB jumped in with her stethoscope. She pressed the metal on to Finn's chest and counted in her head the number of beats per minute. When she was finished, she made a note of the number in her head, and remained underwater with Finn for the next four minutes. The water was too cold to do anything fun, so the two just stared at each other, awkwardly smiling, occasionally coming up for air. After a while, Peppermint Butler stuck his finger and wiggled it in the pool, which was the signal for them to come up.

Gasping for air as they both slowly came out of the pool, Peppermint Butler gave them each a hot towel. They quickly wrapped the towels around themselves on chairs that Peppermint Butler had set up. When PB felt she was warm enough, she removed her towel, grabbed Finn's finger tips and fingered them. After getting an estimated temperature, she hesitantly put her hand on Finn's chest, avoiding his eyes. Tension started building between the two, making the moment seem much longer than it actually was, as Finn stared at her, trying to think what could be wrong. PB felt his eyes on her, gave him quick glimpse and removed her hand from his chest. On cue, Peppermint Butler came up behind Finn, jumped on him and scared him with his eyes. Finn screamed which startled PB because it wasn't the girly scream she was used to. She genuinely laughed as Finn asked "Flip, what the heck, Princess?!" "That was the startle reflex test. And you…" she began calmly but started to giggle again "passed." She flashed him an ever so sweet smile "We should start the other tests now." PB started up the stairs to her lab. Finn, shortly after, followed.

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Jake was getting ready to go back to Candy Kingdom. As he walked downstairs to the living room, Marceline was floating over the couch "Hey Jake."

"Ahhhhh….. Oh hey Marci! Whatcha doin here?" Jake started off scared but relaxed.

"To jam with you and Finn, you weirdo. Where is Finn anyway? I haven't seen him at all in the hour, I've been here." Marceline inquired nonchalantly.

"YOU'VE BEEN HERE AN HOUR?!" Jake asked shocked, gravely thinking of everything he did in the past hour when he THOUGHT no one was here, except for Beemo. A lot of it was embarrassing.

"Uhhh, yeah. Don't you remember? I hide in your house all the time. By the way, you should really wear a towel when you get out of the shower. You never know when someone could just pop in. And WHERE did you get that dress you were playing in? I know someone who would give their immortal soul just to have that dress." Marceline chuckled. "You didn't answer my question. Where's Finn?"

"Finn's at Candy Kingdom with Princess Bubblegum." Jake replied. Marceline immediately asked "He's with Bonnibel, why?"

Jake then remembered a call from PB just the night before. "Do you know how late it is?" Jake begrudgingly answered the phone. PB quickly apologized "Hey Jake, I'm sorry to call at this time. I just called to tell you that no one other than you, I and Peppermint Butler can see Finn. Any added interaction with someone else could be fatal for him. Just try to keep others away until I have finished my analysis of his cellular activity which I hope will be in a 2 weeks. After that, his system should be adjusted to his new body." Jake yawned "Alright" "Goodnight, Jake." PB said before hanging up. Jake let the receiver fall to the floor and then he passed out on his bed.

"Jake…. Jaaaake. Hey Jake! Yoohoo!" Marceline called out

Jake snapped back to reality "Oh, sorry, zoned out for a bit. He's over there helping PB with an experiment. It was at her request."

"Oh, okay. Wanna go spy on them, to see what they're really doing?" Marceline smiled mischievously

"NO! Why would they not be doing an experiment?" Jake curiously asked.

"Oh c'mon, Jake. I know Finny-boy still has the hots for Bonnie. And as for her, I can tell when she has feelings for someone. She definitely has some for Finn." Marceline said informatively. "You're not as fun you are with Finn, I'm gonna go see spy on them." Marceline made a beeline for the door.

"NOOOOOO!" Jake said as he jumped in front of the door.

"What the balls, Jake?!" Marceline asked, wary of Jake's odd behavior.

"Well… um… you changed my mind. I do want to go see what they're doing. But how about we do this: we wait two weeks, you know, just to be sure it's not just an experiment and then we can go spy on them? That way, if they are doing an experiment, then we don't mess it up and they have to start over." Jake quickly retorted. Marceline replied "I guess… well that gives us plenty of time to jam. Just you and me, you know." Jake nodded in relief.

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Over the course of the next few days, PB did a variety of basic tests on Finn that, frankly, if she tried to explain to Finn what they were, he wouldn't understand. She chose to just tell him the names and let him figure out, based on the actions of the test, what she was measuring. It was near the end of the week in which she was done with all of the basic tests. She called Jake over so she could give him and Finn the good news. The three gathered in the lab.

"So boys… I mean men, sorry, it's taking a lot for me to get use to you being an adult, Finn." PB said sincerely "Anyway, from what I have from all the tests I have conducted on Finn in the past week, I have concluded that Finn is currently healthy. His reflexes, running ability, lung capacity, heart, muscles are all of the standard of his physical age. His strength, I must say, is above average but I think that is mainly because of the activities that you two participate in daily." PB smiled as she glanced at Finn and Jake. The two males of the room high-fived each other.

"That's awesome, man!" Jake exclaimed to Finn. Finn nodded "So does that mean you don't have to do those advanced tests then?"

PB replied "Oh no, Finn. I still have to do those. Although, the basic tests have proven that you are currently healthy in your state, they did not prove if your body will be able to sustain this body very long. They did not determine how well your body is using its energy to keep the body you have. I still have to evaluate that."

"Oh, okay. At least, I know I'm healthy right now. So how long will it take you to figure how to reverse what happened?" Finn asked in a limbo of emotions. He did want to turn back to his actual age, but being 19 was really cool.

"Oh well after I see what, your aura is, check your cells activity and a few other things, I should be able to figure out the antidote within a week of the advanced test results." PB answered slightly saddened. She knew Finn would have to go back to his home after he was changed back, but having Finn in such close proximity was… simply wonderful.

"Oh, that's like in 3 weeks. Okay." Finn said also slightly saddened. Jake looked back and forth Finn and Princess Bubblegum, noticing both their demeanor after hearing the news. "Maybe Marceline is right. There's something going on between them."

After discussing some details of the advanced tests, Jake announced his departure "I'm going to go stay at Lady's for a few days. She's gonna be having our puppies pretty soon so, I kinda have to be there, just in case they come early." Finn led him to the door, as PB excused herself to go check on her other experiments. As Finn opened the door, Jake took a long look in the direction PB went, and then stared at Finn. Just before he left, he stretched up towards Finn and whispered in his ear "Don't do anything, I wouldn't bro." he winked. Finn looked at him confused "What do you…" "See ya later, Finn!" Jake exclaimed as he slammed the door in Finn's face.

Finn turned away from the door, still confused. He pushed Jake's weirdness out of his mind and decided he should rest for tomorrow. He went upstairs to his room, sprawled himself on the soft, mint chocolate smelling bed. "Whatever, Jake." He sighed as he put hands behind his head and fell asleep soundly.

A/N: Finn and PB are getting closer! But will they end up together? Who knows? Oh wait, I do! Haha. And how will Jake keep Marceline from going to see Finn? Well, well, you'll just have to read the upcoming chapters to find out, won't you?

I'm really excited for you guys about the next few chapters. Got them planned out already. There will be a lot going on.

Again, thanks to those who read this! Please Review this chapter!

Peace and Love 'til next time,

Spazzy