Disclaimer: I only own the story and my OCs

Happy Birthday, Finn!

The brightness of the sun slowly covered the Grass Lands. It approaches a peculiar-looking tree house. The sun rays gently woke a human boy. The last human boy, or so he thought.

He woke up and saw a yellow dog sitting next to his bed and the dog yelled, "Happy fifteenth birthday, Finn!". Finn sat himself up and said, "Thanks, Jake.". "Now get dressed." Jake threw Finn's usual clothes to his lap. Finn jumped out of bed and changed his clothes. Then, he noticed that all of the windows are closed. "Jake, why are the windows closed?" Finn says as he put on his hat. "We'll get to that." Jake said as he, literally, stretched himself to the stairs leading downstairs. "Come on, Finn. Let's go!" Jake said as he went downstairs. Finn quickly followed.

When he got downstairs, he saw a girl with pink hair and pink dress and her skin is a lighter shade of pink, a girl with pale skin that is floating, and a girl that seems to be made out of fire. "Princess Bubblegum! Marceline! Flame Princess!" Finn yelled.

"Here comes the birthday boy." Princess Bubblegum announced. "I thought I was gonna say that, Bonnibel." Marceline teased which earned her a glare from PB. "Happy birthday, Finn!" Flame Princess ran to Finn and gave him a hug. When they broke the hug, Finn clearly has some burnt marks on his body. "Sorry about that." FP apologized. "Don't worry; I'm already used to it." Finn comforted. "Happy birthday, Finn!" A robotic voice said. Finn looked to his feet and he saw BMO hugging his legs. He reached down and held BMO in his arms while saying, "Thanks, buddy."

He put BMO down and said, "Thanks for coming, guys.". "You should thank your bro here, "Marceline pointed at Jake, "He arranged all this.". "And more." PB added. "More?" Finn turns to his brother. "It's all outside." Jake said with a grin. Finn walked towards the front door and grabbed the handle. He turn around to see his friends (and girlfriend) smiling and nodding. Finn took a deep breath and opened the door.

"HAPPY BIRTHDAY FINN!" A sudden, deafening yell occurred after he opened the door. It was so loud that Finn closed his eyes and covered his ears. When he opened his eyes, he saw what appears to be almost the entire population in Ooo cheering for him.

"How'd you think?" Jake said behind him. Finn turned around to face his bro and said, "Jake, you arranged all of this?". "Yeah, man. You deserved it. 'Cause you're a great friend, a great brother and according to this crowd, "Jake gestured toward the roaring crowd, "you certainly is one heck of a hero."

Overjoyed, Finn leaned over and gave his brother a hug. "This is gonna be the best birthday ever!" Finn exclaimed.

-Later, after some intense partying-

Most, if not all, guests have left, leaving Finn, Jake and BMO the only ones around the tree house. After cleaning up, Finn went to the roof and Jake followed. "Did you enjoy the party, dude?" Jake asked. "Of course, man. It's just that, we didn't get to go on an adventure today." Finn said.

"I know you'll say that." Jake grinned. "Wait here." Jake said before he stretched downstairs. Before long, Jake returned while carrying something behind him. "What you got there Jake?" Finn tried to see what's behind him but Jake enlarged himself so that Finn can't see. "I have three things behind me," Jake said, "and each of them is connected to each other. Guess what it is."

"PB, Marcy and Flame Princess?" Finn guessed. "What?! How are they supposed to be connected?" Jake chuckled. "Well, they're girls and they're all royalty." Finn reasoned. Jake laughed at Finn's silly excuse before showing him the first thing: a polished and sharpened demon sword. "Wow, it looks like new!" Finn shouted. Jake threw it at Finn's hand and Finn said, "Thanks, Jake."

Jake then showed the second thing: Finn's backpack. "Hey, you fixed it!" Finn exclaimed. "Not really, this one is brand new." Jake informed, "Plus, this one is magical. The insides is way bigger than the outside.". Finn opened his new bag and sure enough, the inside is huge. "Cool! Did you buy it from Choose Goose or something?" Finn asked.

"No, I actually got it."

"Got it? From who?"

"From a stranger I met near Mount Cragdor."

"A stranger? What does the stranger look like?"

"I don't know. He's wearing a robe or something so I can't see his face, though his voice sounded old and wise... somehow."

"Hmm... strange." Finn mumbled but then he said, "Thanks though."

Finn wears his new backpack and sheathes his sharpened demon sword. "You know, running around with a new backpack and a sharpened sword is not an adventure." Said Finn. "That's why I have item number three." Jake said as he pulls out the final thing: a notebook. "I've wrote down some requests from people I met while gathering stuffs for your birthday party." Jake explained, "Most of them are to fight something at the Evil Forest though."

Finn grabbed the notebook, read it a little and said to Jake, "Dude, do you know what time it is?". Jake grinned and said, "I think it's...".

"ADVENTURE TIME!" the brothers yelled as they fist bumped.

-Later, after a few hours of adventuring-

A Sign Zombie leaped at Finn and he slashed its head off. Another Sign Zombie charged at Finn and he sliced it in half. A third Sign Zombie caught him off guard and it was going to strike when a giant foot suddenly crushed it. The giant foot shrunk down and is revealed to be Jake's foot.

"Dude, where have you been?" Finn said as he wiped the sweat from his head. "Sorry, man. Those Mechanical Owls are really good at dodging." Jake panted. "Anyway, did we get all of them?" Finn asked. "Let me check." Jake said as he took a notebook from Finn's bag. Jake read a little before saying, "Yep, ten Sign Zombies and twelve Mechanical Owls.". "Is there anymore quest?" Finn asked and Jake read again before saying,"Only one quest left."

"What's it about?"

"We have to slay a creature that's been messin' with some of the safe routes thru the Evil Forest."

"Okay, what's the creature called?"

"That's the thing. I asked around for info about this thing and no one seems to know."

"What does it look like?"

"It's pretty vague, 'cause most attacks happened at night. The clearest description is that is shaped like a goblin but its skin is really pale and the nose and ears are really short and there seems to be fur on its head."

"Did this thing ever... croaked someone?" Finn asked with a very concerned look. "Don't worry, the worst thing this thing does is steal food." Hearing this, Finn sighed in relief.

Finn and Jake then went to the Evil Forest. In ten minutes, the duo reached the outskirts of the Evil Forest. "Where should we look?" asked Jake. "I think we should look around the safe road." Finn answered. Jake agreed and they started searching. After a few minutes, Finn noticed something. Finn unsheathes his sword and put on a battle stance. Seeing this, Jake enlarged his fists and got into a battle stance too.

Finn kicked a small rock toward where he saw something. The response was rather grand. Something suddenly leapt at Finn and managed to pin him to the ground. Finn was able to push it back and get up. He slashed at where he pushed the creature, but the attack only hit thin air. Finn suddenly got tackled from the side which made him fall to the ground.

Seeing this, Jake smacked the creature away with his fists. Jake was about to crush it with his fist, but the creature back flipped out of the way. The creature leapt at Jake and delivered a kick to Jake's face, which left him wide open. The creature managed to land three more punches before Jake grabbed it and threw it away.

The creature landed on the ground but it quickly got back up. The creature noticed Finn charging at it and ducked when Finn swung his sword. Finn continued with an upward slash, but the creature dodged it and in retaliation, the creature smacked Finn's demon sword away. "My sword!" Finn shouted before getting kicked in the gut by the creature. The creature noticed Jake stretching his fist to hit it, but the creature side stepped and grabbed Jake's fist. The creature then swung Jake toward Finn and they both are sent flying. Luckily, they landed near the demon sword. Finn grabbed his sword and got up, ready to fight again. Suddenly, Jake grabbed Finn and started running away, with the creature in hot pursuit.

"Jake, we can't run away!" Finn complained.

"We can't fight in the dark, man." Jake said as he ran, "We can't see it coming. We have a better fighting chance if we fight it in a clearing or something."

Finn hated Jake's idea of running away, but he stuck with it. After a few minutes of running, the duo reached a clearing. Jake dropped Finn and got into a battle stance and so does Finn. After a few moments of tense silence, the creature emerged. Now that there is light, Finn can see what the creature looks like.

The creature's body structure does kinda look like a goblin and its skin is really pale and its nose and ears are shorter than a goblin. There is also black fur on its head. The creature also has red eyes and a loincloth covering its crotch, where Finn guessed is where its vitals are. Finn took another good look at the creature and he is shocked when he realized that the creature's overall appearance looked very... human.

"Jake, that thing looked like a..." Finn started saying but he is interrupted when Jake says, "I've noticed."

Finn realized that the human didn't make any attempts to attack. Finn then decides to do a little experiment. Finn raised his sword, which the human responded by a hiss. Finn then lowers his sword and the human seemed to calm down. Confident of the results of his little experiment, Finn sheathes his sword. "What the...?! What are you doing?!" Finn realized that he should've told Jake first before doing that.

"Calm down, he's not gonna attack us." Finn tried calming his brother down. "How can you be so sure? That thing jumped on you first." Jake said, still in his fighting stance. "I kicked a rock at him. He must've thought it was some kind of attack." Finn reasoned. Jake begins to calm down, but then he said, "Did you just called it 'he'?"

"Yeah." Finn nodded. "How can you know?" Jake asked. "Well, his chest is flat." Finn answered. "Now can you please calm down?" Finn pleaded. Slowly and reluctantly, Jake calmed down.

Finn turned to the human. He was so excited that he ran to him, but he stopped when the human hissed at him. Finn then slowly approached the human. In turn, the human approached Finn as well. Finn raised his hand and rubbed the human's hair. "Jake, we should bring him back to the tree house." Finn said, not letting his eyes off of the human. "What? Why?" Jake complained. "Because we could be the last humans. We have to stick together." Finn gestured to him and the human.

"My name's Finn and his name's Jake. What's your name?" Finn asked and the human looked very confused. "I don't think he has a name." Jake said. "Well, I thought it'll be polite to ask." Finn turned to his brother. When Finn turned back to the human, he looked like he was trying really hard to remember something.

"Whoa, take it easy there guy." Finn said. The human's face lit up, like it just remembered something. Then the human said, "Lex. Me Lex.".

"Okay Lex," Finn said with a smile, "let's get back home."

-Meanwhile-

A cloaked figure stepped into a dark cave. The figure kept walking until it reached some kind of throne. The figure bowed and said, "Master, the second human has been found by the first human.". "Has he come into contact with the sword?" said a figure who is sitting on the throne. "No, Master." The cloaked figure said. "Good, that means Dravia has not been awakened yet." Said the one on the throne.

"General," the cloaked figure stood up, "speed up the preparations. Our plans have to be executed soon." The cloaked figure then left the room. When the cloaked figure left, an orb appeared in front of the one on the throne. In it, there are two boys, one wearing clothes and one only wearing a loincloth, and a dog walking through a grassy plains.

"I'll get you, Finn," the figure turned its attention to the other boy, "and your brother."

Another human?! How can it be?! Who's the figure sitting on the throne? Why does the figure looked at the other human and said "... your brother"? Find out in the next chapter (or the chapter after the next).

Okay, just so I won't get any question, this whole fanfic happened before the episode "Jake The Dad" so Jake's and LR's kids are not born yet, but Lady is still pregnant. One more thing, this Lex is NOT the same Lex from my other stories. This Lex has red eyes, while the Wielders Lex has purple eyes and the Draconia Lex has sapphire eyes. Why do I stress it so much? You'll see... (or maybe read)

XIII IMAGINARY LEX XIII