A/N: Recently got into AT, due to some constant pestering. Just a little idea I'm toying with. Let's see how it goes.

Finn couldn't remember when he started writing stories, but he reckoned it was around the point when Jake went off to college. Right before he left, he handed Finn a present in a wrapped box. A bright red notebook.

"A notebook?" Finn had asked, wrinkling his nose. Jake had let out a calm chuckle, a familiar sound from him.

"That's right. A notebook. I'm not gonna be around to play Knights or Pirates or Super Ninja Zombie Killers anymore. At least, not for a while." Finn still remembered his brother's teenaged face, pushed right up into his. "So from now on, you get to play pretend by yourself."

Finn kicked his feet; at five years old, he was too short for his feet to reach the floor from the armchair. "By myself? How?"

Jake had grinned. "You're gonna write it," he said softly, tapping the notebook. "You learned how to write, right? Spelling and all that shiz?"

Finn had glared from under a mop top of blonde hair. "Of course; I'm five."

Jake nodded; Finn didn't realize until later that he was trying not to laugh. "Aces, bro. Aces. So, from now on, you get an idea for playing pretend? Write it down. And then, when you fill the book, have mom buy you a new one."

A slow smile spread over Finn's face. "I'm gonna write a book?"

Jake nodded. "That's right. A book about us. Where ANYTHING can happen. Where you're the hero, and I'm your trusty-"

"Dog?" Finn interrupted. He had just finished reading "Shiloh" and had made Jake play Dog all morning.

Jake laughed. "I was going to say 'sidekick,' but sure, why not? I guess I can be a dog." He sniffed in disdain. "Just goes to show how much you'll miss me…"

Finn had wrapped his arms around his brother's neck, jostling the woolen aviator cap Jake always wore over his ginger hair. "No, no, Jake," he muttered into his brother's neck, starting to cry. "I'll miss you. I'll miss you forever and ever. And you're still my big brother! Maybe… maybe I was 'dopted by a whole family of dogs! And the mama dog looked over at you and said, 'Here, Jake. This is Finn, our new puppy,' and you said-"

Jake hugged his brother back, hard. "Hey, hey, don't tell me," he murmured. "Write it down."

Finn the Human emerged from his treehouse, blinking and stretching in the sun. He scanned the yard, eyes settling upon the only other person in sight- well, dog in sight.

Jake was sitting cross-legged on the law, hands on his knees and eyes closed. "Hey, Jake!" Finn greeted, nudging the dog's head with the toe of his sneaker. "What are you doing?"

"Hush up, man," Jake responded, keeping his eyes closed. "I'm connecting my mind to the internet, and your chatter is totally killing the vibe." All of a sudden, Jake's eyes snapped open and he stood up with a grin. "Oh, mathematical! Check it out, bro; I just downloaded this sweet dance." Jake started wriggling his arms and legs, stretching them out and shaking his behind.

Finn giggled and started dancing with him. "Algebraic!"

Jake smiled, starting to-

"Tree-house has a dash in it, man," Jake said in Finn's ear, grinning maliciously.

"JAKE!" Finn yelped with alarm, slamming his spiral notebook shut and almost upsetting his cereal bowl in the process. He spun on the spot and glared at his older brother. "I told you- you're not allowed to read over my shoulder."

Jake chuckled, settling into the chair across the dining room table. His bright red hair glinted in the light of the sunrise. "And I'M pretty sure you should be eating, and not writing."

Finn blushed slightly, grinning back at his older brother. "Shut up; I got an idea in the shower and I wanted to write it down." He picked up his spoon and started poking at his cereal once again.

"Big day, today…" Jake said casually. Finn didn't answer. Jake sat forward. "FINN!"

"Huh-what?" the fifteen-year-old said, jumping slightly. His red notebook was sitting under his forearm on the table.

"Big day, dude." Jake rubbed at his forehead, aviator hat sliding up slightly. "Where are you this morning?" He leaned across the table and tapped the notebook. "What were you writing about?"

Finn ducked his head and smiled. "I was remembering when you gave me my first notebook. Remember how I filled it up in a week?"

Jake laughed. "What I remember is an angry call from mom, wanting to know why you had filled an entire notebook with a story about her being a dog. I think she thought you hated her."

Finn felt the same tug in his gut that he got any time someone talked about his mom. A tug that reminded him of the days when he lived in Maine, with lighthouses and the smell of the ocean. When his life wasn't dependent on Jake's job. When he wasn't in a loft in New York, or a flat in Boston, or this two-bedroom apartment with Jake in Vermont. When his mom was still alive…

"Good old mom," Finn said softly. Jake's eyes saddened for a second, but he did his best to smile at his little brother.

Finn heard snuffling near his knee, and looked under the table to find an extraordinarily fat, bug-eyed pug panting expectantly up at him. Finn laughed, slipping the dog a piece of bacon. "Morning, BMO."

Jake scowled, scooping the pug into his arms where it sat, legs stuck out like an overstuffed teddy bear. "His name is Benedict Munchausen von Olaf. He doesn't appreciate it when you call him by that plebian moniker. Do you, sir?" Jake raised his voice in pitch. "Most assuredly not, Jake. It is far too proletariat for the likes of me."

"I say he's BMO," Finn said with a laugh, pointing at the dog with his cereal spoon and sending a dribble of milk across the table. "It's easier to say. And it makes him sound like a robot. You like it, don't you BMO?" The pug let out an aroof, squirming in Jake's lap.

"Look. I bought the thing, I name him. And stop giving him bacon." Jake set the dog down on the floor with a little groan. "Guy's starting to turn into flabby flab-flab."

"He doesn't mean that, puggy," Finn crooned as the pug waddled across the floor. "He's just jealous of your good looks."

Jake laughed, standing up and stretching. "Let's go, broseph," said, scooping his sheepskin jacket off his chair. "School starts in T-minus thirty minutes."

"You're kinda quiet this morning," Jake said aloud. The two had been riding in silence for a while, Finn looking at his shoes while Jake looked at the road. Finn shrugged.

Jake tried again. "I'm digging the hat." His little brother's blonde hair was almost totally hidden under a white, bear-eared hat the two had bought in New York. Finn smiled, but said nothing.

Jake swallowed hard. "Look, dude. I know this isn't how you wanted freshman year to start. But this is a good sign, alright? The principal really liked my resume. And he said they haven't had a music teacher in years. This could be a permanent gig, y'know?"

Finn was silent.

Jake sighed. "Look, dude. Just promise me you'll try to make friends, alright? Put the notebook down for a while. You might be surprised."

The rest of the car ride was silent, except for the constant tapping of Finn's fingers on the cover of his notebook, very close to the title. A title that had adorned every red notebook Finn had ever had, ever since he came up with it ten years ago.

Adventure Time.