Young Harley sat in his garage and typed happily on his new computer, writing out notes on some modifications he would attempt to make on his potato gun. He leaned on his desk and tapped his chin while biting into a cookie, also wondering if some of his ideas were even physically possible without making the gun heavy and awkward. The phone rang nearby, and he tapped the speakerphone button.

"Talk to me." He said, continuing to work.

"You seem distracted." A familiar voice chuckled. "Maybe I should call another time." Harley's eyes lit up, and he smiled.

"Tony!" he said brightly. "I'm just making some plans for my old potato gun."

"Well, from what I can tell, you still haven't tried to adjust the barrel like I told you." Harley blinked in confusion, then spun around to see the multibillionaire standing in his doorway with a cell phone to his ear. He laughed and pressed another button on the phone, ending the call. Tony Stark looked up at him with a curious expression on his face.

"You know, it's rude to hang up on people." He said coolly. Harley smiled and ran over to him, hugging him tightly. Tony chuckled and pat his back awkwardly.

"Take it easy, kid." He smirked, prying him away and inviting himself into the garage.

"What are you doing back here anyway?" Harley asked as the scientist plopped down on the couch.

"I felt I had a right to come back and make sure you hadn't broken the computer I'd given you." Harley smirked and sat beside him.

"Yeah right." He laughed, cuffing him playfully on the shoulder. "You missed me, and you know it." Tony rolled his eyes, this kid loved to test him.

"So, does that bully still mess with you?" he asked, and Harley snickered.

"No way." He giggled. "But I did get in trouble for having that weapon at school." Tony cracked a smug smile and tousled the boy's hair.

"Well, that's what you get for letting the punk bother you in the first place." He teased. Harley huffed and pushed his hand away, looking a bit embarrassed.

"You know something that puzzles me?" The playboy scientist added, glancing at the now empty plate of cookies on Harley's desk. "What kind of cookies did you have?"

"Now, don't start that crap again." The 10-year-old pouted and sat there stubbornly. Tony stood over him and stared down at him. Harley looked away, and even made a move to get up; but Tony moved in front of him.

"Ugh, fine." He finally sighed and stood up, going into his house and retrieving a second plate of cookies. When he came back, he saw Tony over by the computer, looking over his plans and notes.

"You're not a bad artist." He murmured, and Harley just barely heard the compliment. "But I gotta say: some of this is a bit farfetched." Harley rolled his eyes and set the plate down.

"Yeah, yeah, I know. They're just ideas, okay? I make them when I'm bored." An idea suddenly came to him, and he slipped into the chair, quickly typing it out. Tony yanked the chair away from the desk and glared at him.

"What?" Harley asked obliviously.

"You know what I just picked up from that?" Tony asked, with a calm but challenging tone in his voice. "You're saying I'm boring you." Harley smirked and chuckled.

"Well, you do tend to piss me off-" Tony didn't let him finish before prodding him in the ribs with one finger. When the small boy flinched, he sneered.

"Now, what was that?" he asked tauntingly. "I always thought you were so tough." Harley put on an adorably brave face.

"I am tough." He pouted, crossing his arms and getting up. Tony smirked and loomed over him.

"Right. Right." He said simply, standing over the boy as he stood by the couch with his back to the scientist. "Too tough to be, y'know, ticklish or anything." Tony saw Harley shudder at the mere mention of the word and smirked deviously; this would definitely be fun.

Harley, on the other hand, absolutely hated being tickled. It was like a deep, dark secret that only his family members knew; and that he guarded with his life from those punks at school. He was extremely ticklish, and he knew Tony just well enough to know that showing this kind of weakness would screw him over like nothing else. He shrugged apathetically to attempt to play the moment off; but when the scientist actually said the word, he knew he was in for it.

"Uh… I'm not ticklish." He oh-so-obviously lied, staring nervously at his feet. Tony sneered and rested his hands on Harley's shoulders.

"Then I'm sure this won't bother you at all." He dug his fingers into Harley's ribs, pulling the squealing kid toward him before shoving him onto the couch. Harley cowered and giggled, his eyes alight with adrenaline and fear of Tony's tickling fingers.

"N-No!" he whined, trying to retreat into the back of the couch. "Tony, please!" The philanthropist pretended to think it over, then knelt down, and scribbled his fingers over the 10-year-old's stomach and waist. The little boy laughed and shrieked, struggling and trying to curl into a ball. Tony had none of it though and used one hand to hold Harley's wrists over his head, scratching softly into his armpits with the other. He bucked and laughed even harder; Tony knew he'd found a weak spot and released his wrists, quickly digging his fingers in.

"S-Stop it!" Harley squealed, trying to push him away.

"Nah." Tony smirked. "This is payback for all that back-talk you gave me a few months ago." He climbed up onto the couch and dragged his fingers over the boy's sides, squeezing and kneading the soft flesh.

"You should look into working out." Tony badgered, lifting Harley's shirt and tickling his bare stomach. He twisted one finger into the boy's navel, and Harley bust a gut with insane laughter.

"Knock it off, Stark!" he begged through hysterics, hitting the scientist on his shoulder. "You're such an ass!" Tony stopped and pinned Harley's shoulders.

"Could you repeat that?" he said scarily, glaring at him. Harley cowered, knowing he'd screwed himself all over again.

"I didn't say anything." He lied again, and the billionaire sneered, raising his hands and wiggling his fingers menacingly.

"You're a pathological liar, aren't you?" he taunted, lightly flexing his fingers into Harley's flanks and making him recoil with giggles. "Aren't you, you little pest?"

"N-No!" the boy whined, squealing when Tony squeezed his kneecap.

"Wrong answer." Tony held one of Harley's ankles under his arm, and paused before attacking his knees again. "And you know how I know you're lying?" Harley stared at him, puzzled; and distracted by Tony pulling off the sneaker on his free foot.

"O-Okay. Why?" he finally asked. Tony sneered.

"Cause we're connected, pest! Or did you forget?" Tony scribbled his fingers over Harley's socked foot, and gripped his ankle before he could kick him in the head.

"Oh, you did not just try to kick me." Tony turned around, putting both of the boy's ankles in a headlock and removing his other shoe.

"I-It's not my fault, dummy!" Harley shouted, giggling and hitting him with a pillow. "You're the one who was tickling- Hey! S-Stop!" Tony scratched the child's soles, drawing squeals and boyish laughter.

"Now you're calling me names and hitting me with things?" He smirked, pressing his fingers into the boy's feet and scratching faster. "You're just asking for this now." He sat on the couch, keeping Harley's ankles trapped under one arm, and tickling his soles and heels.

Harley was in utter stitches, laughing into the pillow. He'd ended up on his stomach from twisting around in Tony's grip, instantly regretting it when the scientist tickled the backs of his knees and along his spine. Suddenly, Tony's cell phone rang, and he pulled it from his pocket; along with it, he pulled out a pen and smirked.

"You make a sound," he sneered, bringing his legs over Harley's shins to keep them pinned. "And your socks come off." Harley focused on struggling as Tony answered his cell.

"Yeah, Pepper?" he asked. "You enjoying the hotel?" Harley flinched sharply and looked over his shoulder; Tony smirked back, gliding his fingers over Harley's soles while holding the conversation. He would occasionally dig his fingers in and scratch at his toes; and Harley chewed his lip, trying to choke back his giggling. He tried to hit Tony with the pillow again, but the man simply took it and tossed it on Harley's back, leaning on him and continuing to talk to Pepper. The boy rolled his eyes, flinching again when fingers squeezed his side.

That's it; he thought. He reached back and flicked his fingers over Tony's neck, right where his neck met his collarbone. Tony jerked away from him, his voice hitching.

"Tony?" Harley heard Pepper over the phone as a broad smile spread across his face.

"Yeah, honey?" Tony resumed his conversation, tucking the phone between his ear and shoulder, using one hand to push Harley's head against the couch cushion and the other to tickle his side; Harley cringed and started laughing, muffled by the couch. The scientist did eventually bid Pepper goodbye and slipped the phone back into his pocket. Immediately though, he pinned Harley on his back and pulled his shirt up, blowing raspberries on his stomach. The boy went ballistic, laughing hysterically and bucking.

"Knock it off!" he shrieked, the ticklish scratching of Tony's beard driving him up the wall.

"I should kill you." Tony growled with a playful tone, tousling the boy's hair until it fell in his face. "I should tickle you so bad, you go to bed laughing."

"It's not my fault you're ticklish too." Harley giggled, reaching out and tickling Tony's ribs. The scientist flinched and did the same to him, only much worse. Harley snickered and tried tickling his neck, drawing a sudden bark of laughter; the 10-year-old wiggled his fingers over Tony's collarbone and slipped one hand under his arm. The billionaire laughed and pulled the boy's hands away, holding his wrists over his head.

"You are so in for it now." He sneered, picking up the pen he'd pulled from his pocket and biting the cap off it. He lifted Harley's shirt again and doodled on his stomach and ribs. Harley squealed and tried to pull away, laughing and giggling helplessly.

"Quit it! That tickles!" he cried out, recoiling when Tony's fingers dug into one of his armpits.

"It's supposed to tickle, you little moron." He picked the boy up and tossed him onto the couch, grabbing his ankles again. "And now the socks come off."

"What?!" Harley shouted, struggling. "Why?"

"Cause you pissed me off." Tony smirked, pulling Harley's socks off and grabbing the pen, scribbling along the wrinkled lines of his soles and drawing small pictures on his toes and heels. Harley was reaching insanity, his laughter reaching a peak when Tony poked the pen between his toes.

"P-Please!" he begged hysterically. "I hate being tickled!" Tony chuckled, dropping the pen and picking up one of the boy's sneakers. He pulled out the shoelace and threaded it between Harley's toes.

"I'm sure you do hate it." He teased, sawing the thread between the toes and driving him even battier. And then he stopped, letting the boy catch his breath and a bit of his sanity.

"You…" he panted. "You're cruel for a superhero." Tony shrugged and smirked.

"No, I'm not." He argued. "You, Harley, are just a weak, ticklish little baby."

"I am not!" Harley snapped. He struggled as Tony picked him up like one would a toddler, tickling the backs of his knees and his feet.

"Yes, you are." He teased in a babyish tone over Harley's laughter. "Yes, you are, Harley. Coochie coo."

"N-No, I'm not!" he laughed, trying to struggle away. "T-Tony, stop!" Tony sat down on the couch with the boy on his lap.

"I still say you are." He smirked. "And you're gonna say you are too."

"What?! Why would I-?" he was cut off once again by Tony tickling his waist.

"Say it." The scientist prodded. "Say it, Harley!"

"N-Never!" Harley laughed, kicking and flailing. "I won't s-say it!"

"Yes, you will; I can make you!" Tony blew a raspberry on the boy's belly, wiggling one finger in his navel again. He went crazy, bucking and trying to escape. The scientist gripped his ankles again.

"One last round here should break you." He smirked. Harley glared at him, trying to pull his feet away.

"I refuse to be beaten by the likes of you, Mechanic." He growled, and Tony just chuckled, picking up Harley's shoelace again. He quickly tied the boy's toes together, scraping his nails along the soles. Harley went wild with laughter, trying desperately to kick his tormentor or curl his toes. He was no match for the man's strength though, laughing even harder as his toes and knees were attacked as well.

"Okay, okay, I give!" he squealed minutes later as Tony scribbled his fingers along his spine and shoulder blades.

"What do we say?" the scientist sneered, slipping his fingers into Harley's exposed armpits.

"I'm a weak and ticklish baby!" he finally cried out. Tony stopped and ruffled the boy's hair again, standing up and picking up another cookie; He continued to peruse curiously through Harley's drawings and notes. The young boy eventually caught his breath and untied his toes, standing up and sneaking over to the scientist. He dug his fingers into the man's sides, and he flinched and cringed.

"Don't start with me, pest!" he growled through clenched teeth and a crooked smile. He was in too awkward a position to reach the boy though and couldn't stop him from tickling his stomach and drawing an actual laugh. Tony spun the chair around, jabbing Harley in the side; but this time, the boy didn't flinch away. He pounced, starting a tickle fight that was similar to those between a younger and older brother.

It really is a no-brainer who won. Tony was holding the boy upside-down by his ankles, scratching deep into the soles with his pen. Harley surrendered in no time flat, and Tony dropped him on the couch.

"Why are you so good at that?" Harley whined, cuffing Tony's shoulder again. He just chuckled.

"I've had practice." He smirked. "My wife is just as ticklish as you. She probably hates it just as much too." Harley huffed and pouted. Tony smiled and ruffled Harley's hair again.

"Speaking of my wife, I should probably get back to the hotel. I have a meeting tomorrow morning." He stood up and stretched, twitching and glaring when small fingers touched the base of his spine.

"So, will I see you again?" Harley giggled.

"Perhaps before I go home." Tony shrugged, walking toward the door. "If not remember one thing." He stood there, doing some overdramatic, somewhat comical pause.

"Well, what?" Harley chuckled. Tony smirked.

"Stay connected." He smiled brightly, pointing his phone in Harley's direction before walking out the door while the boy waved after him.

Harley walked back to his hand-drawn plans and looked through them, but he was met with criticizing comments in red pen.

"Dammit Tony…" he sighed, chuckling and leaning back in his computer chair.