Start Note: Welcome to my second fanfiction. \(^o^)/
Because there's far too less HeiShin out there (and because this pairing is so damn hot! X3) I decided to write one of my own. I hope you'll like it.

Warnings:
This story will contain Boys Love/Shounen-ai/Yaoi/Slash/Lemon (whatever you like to call it) in later chapters. So if it's not your cuppa tea, you better move on. :)
And on the other hand: If you like your p*rn without plot, you better go with them. ~~\(^-^)

Spoilers: None in particular (if you know Ai and the "medicine" she made, you're good to go).

Disclaimers: Detective Conan/Case closed is the work of the amazing Gosho Aoyama - please support his work!

"Do you have a minute, Kudo-kun?"

The detective boys, consisting of Ayumi, Mitsuhiko, Genta, Conan and Ai, were on their way home from Teitan Elementary. When they were just parting at the usual spot, waving and laughing, Ai stepped closer to Conan and whispered into his ear. The bespectacled boy, who's real identity was the seventeen-year-old senior high school student Shinichi Kudo, turned around to look at Ai Haibara or rather Shiho Miyano, actually an eighteen-year-old scientist before she was shrunk by a toxin she invented herself for a criminal network called "The Black Organization". Long had the young detective tried to bring said organization down, while Shiho had researched a cure for their shrunken state but both to almost no avail. At least the little researcher had developed a temporary antitoxin, which succeeded to turn them back for some hours. But Ai kept it strict to herself to prevent Shinichi from using it constantly to solve crimes, chase the organization or –in her opinion– show off and thereby endanger both their safety.

Now, with the children gone, there was no need to call one another by their aliases or to speak in a childish manner anymore. So Shinichi answered after scanning the face of the young girl: "Sure. Did you find out something new about the toxin?"

"What makes you think that?"

"Your face told me."

"My face?" She smiled and raised an eyebrow. "Very observant, Meitantei-san." She called him that occasionally when his deductions bothered her. Or just to throw him off for fun. It worked most of the time. "Let's go to the Professor's house and talk there." Shinichi nodded and they continued walking.

At the laboratory in the basement of Professor Agasa's house, they sat down and Ai poured both of them a cup of coffee. While passing her guest the cup, she said in her usual calm manner: "I might have found a way to turn us back for good."

Shinichi nearly spilled his coffee on hearing that. "Honestly? How?"

"Keep your shirt on, Kudo-kun. I said I might have. So far, it's just a theory." She took a sip of her coffee and looked at the excited boy and his now glowing eyes before she sighed and continued talking. "It might not result in wearing off the toxin's effects constantly, and there's a chance that it won't work at all, but I looked through the analysis of the toxin's effects I made so far and discovered a possible way to annul the toxin naturally…"

Shinichi nearly couldn't sit still anymore but knew better than to press Ai. She wasn't prone to that. So he stayed quiet as she turned to her computer, and after opening some files, looked at them. After a while she took a deep breath and asked without turning back to him: "What would you do to turn back?"

Shinichi thought about his answer. He wanted to say everything but knew she asked for a purpose. So he contemplated his answer and finally said: "A lot."

She smiled to herself and muttered: "I knew your answer would be thoughtful." Again she took a breath and then asked without any further ado: "Did you ever have intercourse?"

The azure eyed boy stared motionless. He wasn't sure he'd heard her correctly. Did she really just ask… that? "What…?"

"I mean it the way you think I do." She turned around, her expression blank as usual but with a light shade of pink on her cheeks. "So, have you?"

"Why…" Shinichi began, feeling his own head getting hot, but then collected himself. He breathed deeply and then stated calmly: "No, I haven't."

Ai nodded and turned back to her computer. "Then this will be even harder…"

-'.- - * - -.'-

Shinichi sat on the couch in the Mouri detective agency. He held his mobile phone in hand, still unsure how to say the things he had to. He considered texting but decided against it for the topic he had to discuss was somewhat... difficult. A loud laughter came from behind the couch. Kogoro Mouri sat at his desk watching a show he recorded starring his beloved idol Yoko Okino. He hadn't had a case for some days now and slacked off, as he always did when he wasn't occupied. Ran was still in school but would come home soon. So time was running short for this call he had to make privately.

He looked at the phone again and stood up. Better to get it over with now. Any delay could only lead to unsettle him further.

"Oi, where you going?" Kogoro's voice came from behind Conan.

"Just upstairs, gonna do my homework."

"Oh, okay then." And with that his focus was back on Yoko again.

Shinichi took his backpack and hurried to the apartment above the office. He opened it, took out some of his books and pencils and arranged them on the table. If Ran or Kogoro were to check on him, they would find him in the middle of doing his homework, as stated earlier. But for now, he sat by the window so he would see when Ran came home. Again he looked at his phone. He knew the hard part wouldn't be happening today, but even so he couldn't bring himself to dial the number. This was a stupid idea but it was the only one he could think of. He had tried to come up with alternative plans but every single one of them was even worse. So this was really not his best but apparently his only option.

He looked at his watch and realized that if he didn't call now, he couldn't do it today anymore, so he finally searched for the number in his contact list and pressed 'call'. The ringing seemed to hall in his ears and for a second he wished the other one wouldn't answer. Finally there was a click and a happy voice said a little too loudly: "Hello?"

"Hello Hattori, it's me. Are you busy?"

"Hey Kudo! What's up? Nah, not really busy, even bein' the best detective my age apart from ya'self!" Cheery as always, Shinichi thought. He wasn't sure if that would make things easier or harder. "Hattori, I have a favour to ask. A really big one, to be honest..."

"Sure thing, Kudo. Whatever ya need. Is it a case ya want my help with?"

"No, not exactly. And I'd suggest you listen to the favour first before agreeing to help."

A short pause. "Hey Kudo, is everythin' okay on your end? Ya sound... kinda troubled."

"Well, one could say so. But don't worry, it is nothing too serious. Could you come over to Tokyo this weekend?"

"Hm, well... Sure. I have no plans. Do ya want me to bring Kazuha along? I'm sure she would love to see ya Nee-chan again." Heiji called Ran always that, at least when she couldn't hear it. It started as teasing but by now Shinichi didn't even realize it anymore.

"Uhm, you see..." Shinichi paused and swallowed a few times not sure how to put this.

"Kudo?" The voice of his osakan friend sounded worried.

"Hattori, could you come alone? And to be frank, if you can come, could you do so without telling anyone where you are going? Especially not Kazuha. Or Ran for that matter."

"Are ya sure everythin's okay?"

"Yes, but it is really important... to me." He rubbed his forehead. That sounded way too dramatic.

"Okay, that's all I need to know. Will Saturday around noon do?"

Shinichi was relieved and troubled at the same time. That was Heiji Hattori for you. Acting in times of need, questions could wait. The detective of the east would have been a lot happier to know such a good friend if he didn't felt like a damsel in distress. Nonetheless smiling, he answered: "Yeah, that's fine. Can you come to my house? I'll mail you the address."

"Sure, I'll book a train seat right away. Okay then, see ya Saturday."

"Yeah, okay. And Hattori?"

"Yah?"

"Thank you. Honestly."

"Aw, don't mind it. And besides, I didn't say yes yet." His laugh was refreshing. "So, see ya Saturday."

"Yes, till then." They hung up. Shinichi shut his phone and rubbed his hair. This was going to be a hard weekend. Or rather an awkward one.

From the stairs Ran's voice called: "Hi Conan. I'm home." Quickly he jumped up and ran to the table just in time before the young brunette entered the room. "Welcome home, Ran-neechan!"

Author's Note:

-kun
Suffix, used for men and boys, but also by seniors to address juniors, or teachers addressing students
(Trivia: Professor Agasa mostly addresses Ai with Ai-kun)

-san
Suffix, polite and gender-neutral

-chan
Suffix, used for/by children and teenagers, also for women or close friends (many Japanese women like to be referred to as cute)

-neechan (also -neesan; polite: -oneesan)
Suffix, used for blood-related older sisters or a young women older than oneself

Beta-Reader: My dearest Tojatic - He did his very best, so if there are any faults left, they're on me.

Please leave a little review, if you made it till here. I highly appreciate it.