"Hiro, My Little Test Subject"

By MaturePopcorn

Description: When Tadashi decides to make Baymax, he needs a LOT of information for him about people and the human body. But Baymax can only learn so much from books and the internet; some of it has to come from real-life experiences. And who better to help Tadashi than his own brother…

WARNING: Is a warning really necessary? You clicked on a RATED M+++ FIC. TRUST ME; UNLESS YOU'RE NINE, YOU KNOW WHAT YOU'RE GETTING INTO. So no warning is needed, right? No? Good.

Author's note: STOPSTOPSTOP DROP EVERYYYTHIIING…! BIG HERO 6 IS OUT, NOTHING ELSE MATTERS. I WAS in the middle of writing a Naruto x Gaara fic. (Which I'll finish and post within a week; see my account later…), when I went to go see Big Hero 6 with my friends. I had high expectations…

…And I was not disappointed.

All other fanfictions are being placed on hold until this one-shot is completed and posted. Sorry for the (not really an) inconvenience.

Much love,

~Kisa Alvarez

Chapter 1

Tadashi leaned back in his chair and sighed. He had been searching for hours, but couldn't find what he was looking for… Porn. But it wasn't for him. He NEEDED Baymax to learn everything about the human body, including sex, and simply giving Baymax an internet Sex Ed. class wasn't enough; he had to show Baymax videos of it actually happening to get the fullest amount of information. The easiest place to get videos was a porn website. However, Aunt Cass strictly monitored the internet (mainly for Hiro) and the college blocked porn. The only thing he could think of was live sex, which he could film and upload to a disk for Baymax. But Tadashi seriously doubted that anyone at the college would actually let him use their bodies for science, as much as they all loved it and respected Tadashi. He tried to think of another way, to "look for another angle", but all he came up with was frustration and annoyance.

"Tadashi! Hiro! Dinner's ready! I made pizzaaas!"

Hiro bolted from his bed over on the other side of the screen and ran downstairs, grinning and singing, "Yeaaah, pizza…!" He slipped and fell on the bottom stair, quickly standing back up. "I'M OKAY!" He ran over to his chair and sat there, wide eyed, waiting impatiently. Tadashi slowly followed him, sitting down next to him. He looked at Hiro and rolled his eyes, smiling. "Crazy kid…" He looked around the table, but there were no plates. He looked up confused. "Umm… Aunt Cass?"

Aunt Cass smiled at Tadashi, "I know; the dishwasher just finished drying the dishes. Hiro, can you go get some plates while I take the pizza out of the oven?"

Hiro got out of his place. "Sure, Aunt Cass." He walked over and opened the dishwasher. Tadashi happened to be watching him, and when Hiro bent over, Tadashi's eyes wandered to his brother's butt. He blushed and looked away, but he couldn't stop himself from looking again. "H-has Hiro always been THAT cute?" Tadashi blushed harder and looked down, mortified at the thoughts circulating in his mind. Hiro set the table and sat down, looking at Tadashi quizzically. "Hey bro, you okay?"

Tadashi looked at his confused face, and something in his head instantly clicked. He smiled and tussled Hiro's hair. "Yeah, just thinking about something. When dinner's done, I wanna show you something I've been working on, 'K?"

Hiro grinned. "Sure!"

Aunt Cass sat down and put the pizza on the table. "You boys okay? How was school today, Tadashi?"

Tadashi served himself some pizza. "Good. I'm almost done with my 'project'; I just need one more thing."
Aunt Cass smiled. "That's great! If you need, I can go get it. I'm going out to the store, but I have to go all the way to San Rasaka; United Markets is the only place I can get all my stuff." She looked at them warily. "You won't burn the house down with one of your experiments, right? You won't get arrested?"

Both boys rolled their eyes. "No, Aunt Cass…"

Aunt Cass smiled. "Good! So, what was it you needed?"

Tadashi looked up with a mouth full of pizza. "Yu knt git it nt ha stohre."

Aunt Cass's left eye twitched. "Tadashi, that's disgusting."

Tadashi swallowed. "I said 'you can't get it at the store.'" He glanced at Hiro. "It's not something you can really buy, it's information."

Aunt Cass took a sip of wine. "Well, I should be back in two hours or so."

Hiro looked at Aunt Cass judgingly. "Should you be drinking that if you're driving?"

Aunt Cass laughed, "I'm only having this one glass, Hiro; I'll be fine."

Hiro shrugged and kept eating.

Tadashi smiled. "Two hours, huh? That's all the time I need…" He thought, glancing over at Hiro every now and then.

When they were done with dinner, the two teens headed upstairs while their Aunt Cass left for the store.

"Be safe, and don't go outside!" she yelled upstairs. "It's dark, and KRON4 said it's going to rain tonight!"

"We won't Aunt Cass! We'll be good!"

Aunt Cass smiled and locked up the door behind her, leaving Tadashi and Hiro alone in the house together.

Hiro walked over to Tadashi's side of the room. "So, big bro, what were you gonna show me?"

Tadashi grinned really big. "Well, you know that 'thing' I'm working on?"

Hiro sighed. "You mean the one you talk about non-stop but never show anyone? Yeeesss… What about it…?"

Tadashi looked around at the messy room until his eyes settled on a camera. "Well, it's a robot, like the ones you make. Only thing is, I'm missing some key information, so I was hoping you could help me." He walked over to the camera he had got for his twelfth birthday and set it on a tripod. He looked at Hiro. "'K?"

Hiro nodded. "I guess. What kind of information?"

Tadashi shot Hiro a half smile and turned the camera on. Then, after pressing play, he took his shirt off. "Come here, lil' bro."

Hiro warily walked across the room to Tadashi. "What are you doi-HEY!" Tadashi grabbed Hiro's waist and pulled his pants down around his ankles. Hiro squirmed away and fell down. "W-what the hell are you doing?!"

Tadashi grinned. "Come on, I need this to finish my robot."

Hiro looked at Tadashi with a full look of WTF. "What… You…? No! I-I'm your BROTHER!"

Tadashi looked slightly annoyed. "You don't even know what I was gonna do."

Hiro whimpered, causing Tadashi's dick to get harder. He unbuttoned and unzipped his pants, pulling them down a couple inches so his bulge stuck out. "But… You probably guessed right anyway…"

Hiro blushed insanely red and backed up a few feet, into his dresser. The honest truth was that he had these fantasies all the time; he usually jacked off at night to the thought of Tadashi "doing things" to him. But now that Tadashi really wanted to do them, Hiro was confused and alarmed. "I mean… I want it sooo bad, but Tadashi is my BROTHER!" Hiro glanced up at his big brother. "And… I'm 14, he's 19… It would be illegal even if he wasn't my brother! He could get in serious trouble."

Tadashi sighed and looked at Hiro. "Hey, lil' bro. Your bulge is sticking out."

Hiro looked down and decided, right then, that he definitely needed this. He squirmed a little in embarrassed anguish and emotional agony, rubbing his tip against the front of his underwear, sending waves of pleasure down his body. "I… I guess we could maybe do a LITTLE before Aunt Cass gets home…?"

Tadashi smiled wide. He walked over to his little brother and got on his knees, lifting Hiro's shirt up and using his tongue to feel every inch of Hiro's chest. "T-Tadashi… Nnghh…!" Hiro blushed harder than he thought physically possible and looked down at Tadashi. "T-this is so… Wrong! I-I don't think we…"

Tadashi put his first two fingers on Hiro's lips and hushed him, smiling. "Don't think at all. Just let your instinct take over." He then leaned in close to his little brother's mouth and gently brushed their lips together before pulling away to softly bite Hiro's neck, moving down onto his collarbone. He kissed him softly, working his way further down to his bellybutton, before rubbing his head against Hiro's chest quietly. "You know, I really love you, Hiro."

Hiro breathed in and moaned softly as Tadashi pulled the band of his underwear down, sticking his hand down where his boyhood stuck out, hard as a rock, pushing against Tadashi's prominent boner. He looked at Tadashi with eyes of submission and breathed, "I love you too, Tadashi."

Tadashi smiled with genuine love and pure happiness. He reached down and grabbed Hiro's shaft and balls with one hand, using the other to pull down his little brother's underwear lower so his boyhood was fully exposed. He brought his face back up to Hiro's and, more forcefully this time, pressed his lips against Hiro's and forced his lips apart with his tongue, ramming it into Hiro's mouth all the way back to his throat. Hiro squirmed and moaned loudly, pushing back and digging his nails into Tadashi's back as he began to pump Hiro's dick, sending more waves of pleasure down Hiro's body. Tadashi grinned and looked at Hiro with eyes of pure lust before taking his hand away from his brother's crotch. Hiro whined, "N-no…! Don't stop…"

Tadashi breathed heavily, "I'm not, lil' bro; don't worry, I have something even better…" He moved down until his face was directly over Hiro's crotch, burying his face in it. He wrapped his lips around one hairless ball, then the other, and wrapped his hand around Hiro's cute little body so he could hold his ass in his hands, squeezing it gently. Hiro moaned softly and grabbed Tadashi's hair with his hands. Tadashi moved his fingers over and stuck two of them a cm. up Hiro's tight little hole. Hiro gasped and dug his nails back into the back of Tadashi's head, making him wince in pain.

"S-sorry…! But… You…"

Tadashi slowly shook his head, not wanting to dare lose Hiro's taste. Instead, he slowly forced his fingers up further into the hole until they were in up to his knuckle. Hiro was moaning every other breath by now and felt like he was on ecstasy, wanting nothing more than this feeling to last forever. He started slowly grinding on his big brother's hand to make it feel even better, forcing the fingers in and out just a little. He looked into Tadashi's eyes expectantly, and Tadashi answered his silent pleas with his mouth, taking the balls out and putting Hiro's tip into his mouth. Hiro was only about 11 cm. but it was still enough to fill Tadashi's mouth when he put it in deeper. He even went as far as fitting the whole thing in his mouth AND putting Hiro's balls in his mouth, filling it to the brim with his little brother's husky tasting, hairless crotch. Hiro let out a loud moan of pleasure and softly screamed, "Tadashiii…!" He pulled on Tadashi's hair, forcing his big brother to suck with increasing force and determination.

Within five minutes, the younger teen couldn't take it anymore. He came, with a huge moan, directly down Tadashi's throat; the smooth, creamy, hot liquid streaking down and spilling out his mouth, leaving white puddles on Hiro's inner thighs and the bed sheets. Hiro put the back of his hand over his mouth to stop from screaming too loud, moaning Tadashi's name so loud they were convinced the neighbors could hear. Tadashi slowly took Hiro's boyhood out of his mouth, leaving a thin line of cum and precum from his mouth to Hiro's tip.

Tadashi's erect boner felt like it was going to burst from non-use, and he looked at Hiro's quivering, naked body lying on the bed. Hiro now wore nothing but black half-knee socks and his underwear was down around his ankles, which turned Tadashi on even more, if that were even possible. He grabbed Hiro's waist and butt and slowly flipped him over onto his stomach, to which he made soft noises the whole time. He forced Hiro's cheeks apart and looked at his little brother's tight little hole, which was barely stretched at all from his fingers. He grabbed Hiro's wrists and forced him onto his hands and knees; he then climbed over Hiro and mounted himself right above his hole with his 21 cm. cock. Hiro whimpered softly. "T-Tadashi… Will this hurt? You're so big…"

Tadashi blushed like crazy. "I-it might a little at first, like my hand did… But it'll feel really good soon, I promise…" Using nothing but sweat and precum as lube, Tadashi slowly forced his cock into his little brothers hole. Hiro moaned, softly at first, then VERY loud, and when Tadashi stopped halfway in, Hiro thrust backwards to ram the rest of it all the way in.

He stopped, and he felt a severe pain in his ass. He looked back to see that a small amount of blood was dripping onto the bed from where Tadashi's too-big cock ripped his boy-hole a little. He whimpered a little, but when Tadashi tried to take it out in panic, Hiro practically screamed, "N-NO!" Tadashi looked at Hiro with angst and concern. Hiro looked at him with a pleading face. "P-please don't… I've been fanaticizing this for 3 years… D-don't stop now…" Tadashi nodded and slowly pushed himself back in all the way. He began to thrust slowly, doggystyle, riding his little brother's ass with his entire crotch. He moaned as he felt Hiro's walls tighten up every time he went deeper.

Tadashi gasped as he felt something warm lap at his knees; he looked down to see that Hiro had peed himself. Hiro looked embarrassed, but neither of them could stop now. He continued thrusting until he couldn't take it anymore, spilling his hot seed deep inside Hiro's ass, streaking it along his walls and spilling out onto his butt and Tadashi's crotch. He pulled out and slowly crawled over to the camera and turned it off. He looked at Hiro, who was already beginning to fall asleep. He smiled and, feeling his exhaustion too, he picked Hiro up and carried him to Hiro's bed, which was clean. "I guess we'll just have to clean up tomorrow…" He heard the phone ring downstairs, but decided to just leave it, opting instead to crawl in next to Hiro. He quickly fell asleep against his little brother's naked body, hearing Hiro's soft breaths and quiet heartbeat fade into the blackness of sleep…


"This is Cass; I'm not here at the moment, so leave a message and I'll get back to you as soon as I can. Thank you!" *BEEP* "Hello? Boys? The storm is getting pretty bad, so it looks like I'm gonna spend the night in a Marisawa hotel. I'll see you around noon tomorrow. YOU BETTER HAVE A GOOD REASON TO NOT ANSWER! YOU BETTER BE SLEEPING AND NOT IN JAIL! 'K love you guys!" *BEEP*

Authors Note II: Oh my… I… Didn't expect that… Either way, I'm tired, but I hope you guys like it! I'll keep this Authors Note short, so I will see you all in my Naruto fic!

Songs I listened to while typing:

Magical Mirror (Len and Rin Kagamine)

The Wolf that That Ran Away with Little Red Riding Hood (Len and Rin Kagamine)

The Sea of One Thousand Fathoms, The Shore Sands of Ten Thousand Miles (Len and Rin Kagamine)

Corrupted Flower (Len and Rin Kagamine)

***EXTRA NOTE***

You guys REAAALLY wanted it, so chapter two will be out at 6 in the morning, California time (or earlier!), January 1st, 2015. :D :D :D