Hattori had grumbled profusely about having to host Kaitou KID for the weekend, but he didn't actually mind that much, really. Sure, he kind of hated KID for making a fool of him with that Kazuha disguise, and he was still immensely irritated at Kuroba for kissing his best friend right in front of him. He was also pretty hurt that the crazy magician was invited to the real strategy meeting while he himself was not; doubly so because of the entirely legitimate reasons that he understood and agreed with. But actually hosting Kaitou KID for the weekend gave him plenty of opportunities to prank the guy, so he fully expected to enjoy the time.

Kudou had warned him that Kuroba was deathly allergic to fish, and he made Hattori promise not to do anything to actually hurt him. Hattori did want to stay on his best friend's good side, but he was also fully confident that he'd be able to find more subtle ways to annoy the obnoxious thief to death. Come on, Hattori was a certified genius and crime scene expert! If he wanted to set up a trick that left absolutely no evidence about the culprit, or just behave as obnoxiously as possible while still maintaining plausible deniability, why, not even the 'great' Phantom Thief would stand a chance against him!

As his first (and very minor) prank, he'd bought a new T-shirt specifically for today that he hoped would embarrass the thief when they met up outside the train station. It was a plain white T-shirt with the KID caricature emblazoned across the front in thick black lines. Not that Hattori would ever reveal the guy's secret identity (not intentionally, anyway), but he did want to poke fun at him as much as possible for it.

"No. Way." Kuroba's voice drifted toward him through the crowd of passengers exiting the newly arrived train. Hattori smirked mischievously at the notes of disbelief and incredulity he heard, until he turned and caught sight of the other teen and gritted his teeth to hold back a grimace.

"What are the odds that we'd be wearing the same shirt?!" Kuroba's face split into a horribly irritating grin, then he ran up and brazenly swung an arm over Hattori's shoulders. "Come on, we gotta get a selfie to commemorate this occasion!" He then immediately texted the selfie to a newly formed group chat of himself, Hattori, and Kudou. Hattori's traitorous best friend replied immediately with several jabs at him for his grumpy expression.

— Round 1 Results: Kuroba 1, Hattori 0 —

"So what now, boss?" Kuroba asked cheerfully.

"How 'bout some dinner? Ya like spicy food?"

"Sounds good! Are we walking?"

"I brought my bike. Hope yer not afraid of a little speed."

"Ooh, sounds fun. Let's go!"

Oh, it would be fun alright. For Hattori, that is. He was extremely competent with his motorcycle and knew he could drive at ridiculous speeds and even perform advanced tricks safely. But the unsuspecting magician did not know that, so Hattori intended to put a healthy dose of respect into the guy by giving him an innocent little scare with his seemingly reckless driving.

"What's with that evil grin? Are you planning something fun~?"

"Oh no, nothin' at all!" Hattori responded, internally cursing his utter lack of a poker face. Oh well. There was nothing Kuroba could do to escape at this point anyway. "Here's yer helmet. Now hold on tight, cuz I like to go real fast!"

The plan worked beautifully — it only took a few minutes on the highway before Kuroba commented on it.

"Hey, Heiji! Come on, you're going to get us both killed driving like this!"

"Who said ya could call me by my first name? And don't worry, I know what I'm doin' here!"

"No, I'm serious! You're taking these turns way too hot — I'm going to get thrown off!"

"Not if ya hold on properly and—" but even as he spoke, the weight behind him suddenly vanished in the middle of the (admittedly too fast) turn off the highway and onto the bridge toward downtown.

Hattori gasped and skidded his bike to a stop, swinging around to the shoulder of the road and jumping to his feet to lean over the safety railing on the side of the bridge. His heart was caught in his throat, simultaneously frozen solid and beating so fast it hurt. Had he actually just killed or injured Kudou's boyfriend and crucial member of their team?! Oh no, this couldn't be happening, no—

"See? That's what it would've felt like if I'd actually died because of your driving. Feels bad, doesn't it?"

Hattori whipped his head around looking for the source of the teasing sing-song voice, but couldn't see the thief anywhere behind or to the side… he slowly glanced up and scowled at the man who was perched in the rafters of the bridge and waving a grappling hook device at him.

"Ya nearly gave me a heart attack, jerk! Ya got a twisted sense of humor, ya know that?!"

"Oh? I have a twisted sense of humor?" The tenor of his voice implied that he very much knew that Hattori had been trying to pull the exact same sort of prank on him mere moments ago. Caught red-handed and not wanting to talk about it any further, Hattori quickly changed tactics.

"Just get down here before we get a ticket for loiterin' on the side of the road!"

"Not until you give me the keys and let me drive the rest of the way~"

— Round 2 Results: Kuroba 2, Hattori 0 —

The restaurant that Hattori had chosen for dinner to welcome his new 'friend' to Osaka specialized in spicy food. The plan here was to order the spiciest thing on the menu, ask for it to be made extra spicy, peer pressure the other into getting the same, and then pretend to be wholly unaffected by the spiciness while the supposedly 'undefeatable' Kaitou Kid squirmed in discomfort.

Well, the first three steps had gone according to plan, and Hattori was successfully putting on an act of nonchalance, even hiding the faint pink in his cheeks and the fact that he had started to sweat from the heat of the meal. But unfortunately, it seemed he'd underestimated Kuroba's acting skills, because the psychopath just kept complaining about how bland the food was and adding more hot sauce to it. Every time he did, Hattori would take the bottle from him and add more sauce to his own plate as well, refusing to be outdone.

Eventually, the frustration combined with the lightheadedness brought on by the extreme spice caused him to lose his temper. He asked the waiter to bring a second bottle of hot sauce, which he promptly uncapped and immediately began chugging while maintaining intense eye contact with his new rival. Utterly unintimidated, Kuroba took up the other bottle and chugged it as well.

After a few gulps, Hattori's survival instincts finally won out, and he tore himself away from the bottle and sprinted toward the bathroom to hold his face under the sink faucet and maybe throw up a little. When he returned, Kuroba's plate and both bottles were empty, and he had already ordered dessert. Spicy desserts with cinnamon and ginger.

— Round 3 Results: Kuroba 3, Hattori 0 —

The next prank was a little bit meaner, but Hattori felt he was entitled to some of that by now. He led Kuroba to the guest room in his house, where he'd previously installed several tiny speakers programmed to play very minor but increasingly unnerving noises throughout the night. It would be the sorts of creepy noises one might hear in a horror movie, starting off with faint creaks or breezes, gradually moving to less subtle sounds like doors squeaking and people whispering and creatures growling, and culminating in a recording of a small child giggling that made even Hattori shudder.

The basic plan here was for the 'amazing' Kaitou KID to get so scared of a few innocent sound effects that he would come crying to the nearest detective for help, who would then graciously 'solve the case' for him. Hattori hurriedly said good night before his devious snickering could give away his plans, then he went to his room to watch the clock and wait for the inevitable cries for help.

Apparently the prank was a little scarier than Hattori had anticipated, because halfway through the scheduled sound effect show, a dreadful bone-chilling scream shocked him out of bed. He raced down the hall and threw open the door to the guest room, then simply stared in open-mouthed horror at the sickening scene of red goop splattered about the center of the room. Hattori covered his mouth with a hand and looked away; even someone who encountered murders as often as a detective didn't usually have to face something so gruesome. But no! He forced himself to look again and start investigating. He was responsible for making sure this guy was ok, so he had to do whatever it—

"Oh hey, Heiji!"

Hattori shot into the air like a spooked cat at the cheerful voice that suddenly piped up from behind him.

He spun around to see the magician holding some towels and pouting at the mess in the room. "I accidentally dropped my spare bottle of hot sauce! Such a pity, I was really looking forward to drinking it later."

"..."

"Oh, and I think some might've gotten on your cute little toy speakers too. A terrible tragedy, really."

— Round 4 Results: Kuroba 20, Hattori 0 —

Hattori grumbled over his breakfast. He hadn't slept well at all, and it wasn't just because of the lingering adrenaline from the scares or the stomach cramps from all the hot sauce. No, he'd been awake most of the night scheming. After the disastrous first day, he'd been forced to discard most of his other ideas. Which left him here, at breakfast, casually watching Kuroba out of the corner of his eye to see if he would fall for the old classic 'I loosened the lid of the salt shaker and now all the salt has poured out on your food' prank. So he was grumbling at the fact that this prank was really the best idea he could come up with.

At long last, Kuroba did reach for the sabotaged salt, held it over his food, and… a normal amount of salt came out.

Hattori couldn't resist: he had to know what had gone wrong! He snatched up the salt and tipped it over to examine the seal… and the lid popped off and emptied the entire contents all over his breakfast.

He stared at it blankly while Kuroba filled the room with his joyful laughter.

"Ahhh, a true classic!" the idiot thief sighed after way too much merriment, pretending to wipe away a tear. "Yeah, that's one of my favorite pranks to pull on Hakuba."

"Huh? You know that arrogant British prick?" Hattori immediately perked up at the distraction, like a dog reacting to a squirrel.

"He's my classmate. Which is exactly as annoying as it sounds, but, to his credit, it is really nice to have such a convenient and constructive outlet for my pranks."

"Now this I gotta hear! Tell me all the worst things ya've ever done to him, and spare no embarrassing detail!"

Kuroba grinned, a bright and mischievous thing that lit up his whole face, then began describing in excruciating detail all the curious misfortunes that had befallen Hakuba ever since the day he first transferred to Ekoda High. And just like that, they were friends.

— Round 5 Results: Who cares? Hakuba is the real loser! —

They spent the day sightseeing. Sort of. Kaito had been to Osaka before as his alter ego, and Heiji lived there. But running around the city in "I 3 Osaka" T-shirts and taking ridiculous touristy photos was a great excuse to be in random places so that the thief could get close enough to their targets to (pardon the expression) work his magic. Plus, it was a great opportunity for them to spam the group chat with photos that Conan pretended to ignore but always viewed immediately. They shared a good joke or two at his expense. It was a good time.

The one thing that still really annoyed Heiji was Kaito's insistence on using his first name all the time, which was far too much familiarity for Heiji's liking. Only Kazuha was allowed to be on a first name basis with him! But he did start to see the sense of it when they arrived at the police station that afternoon. Ostensibly, this was the final leg of the 'tour,' where Heiji would show his new friend the place where he and his dad worked. They first went to his dad's office, and Heiji introduced them, then waited in confusion while both just sighed in frustration and shook their heads.

"We're very lucky that you had the foresight to close the door behind you when you entered the office," Hattori Heizo addressed Kaito after several moments of tense silence.

"It's not the first time this has happened," Kaito admitted ruefully.

"What? There some kind of problem here?" Heiji demanded.

"Do you not realize that you just introduced your friend to me as 'The Kaitou KID, International Thief 1412'?"

"...oops."

"Not 'oops,' Heiji!" his father bellowed, slamming his palms on the table. "This is serious! I assured Yuusaku that it would be safe to include you in the plans, but you're going to get people killed like this! One more time, and you're off the investigation for good, you hear me?! I don't care if I have to send you to a boarding school out of the country to keep you out of it. I will not allow you to jeopardize the entire mission with your carelessness!"

Heiji stiffened under the rebuke, angry replies on the tip of his tongue, but he held himself back. He knew better than to talk back to his father, especially since he might even have a point this time. So Heiji glared at the floor and said nothing.

Then a friendly arm slung over his shoulders, and Kaito contributed his thoughts, in a much calmer and kinder tone. "See, Heiji, this is why I thought it'd be nice if you could call me Kaito. That way you can always just use the same name whether I'm in costume or not, since it's so similar to Kaitou."

"Y-yeah. Ok, that's a good idea, KI- er, Kaito…"

"Right, ok." Kaito patted his shoulder then smiled at Heizo. "Don't worry, Hattori-san, I'll help him out!"

Heizo seemed to trust the thief far more than he trusted his own son. So he solemnly shook Kaito's hand and sent them on their way.

Heiji wondered what that comment 'I'll help him out' could possibly mean, until the very next time he went to introduce Kaito to one of his dad's coworkers. Right as he was about to say "—and this is Kaitou KID" he was cut off by his own voice from his own mouth saying "—and this is Kaito."

It threw him off so much that it took a second to remember about KID's voice imitation abilities. And apparently ventriloquism too? But since Kaito continued with the same trick for every single introduction, Heiji almost got used to it by the end of their visit to the station.

—

The walk back from the station was quiet. Or it would have been, except that somebody apparently had a compulsive need to hum Two-Mix songs the entire time. Not that it was unpleasant, really. The guy could certainly carry a tune. But now the song was going to be stuck in Heiji's head all week, and Kazuha would definitely tease him for years if she caught him idly singing La vie en rose to himself. Ug, how troublesome.

The humming only stopped when they finally reached the Hattori household and Heiji demanded to know if Kaito had finished what he had to do at the station.

"Of course!" he replied, mock offended. "Just who do you think you're talking to?"

"I didn' see ya get close to the guy at all!"

"Why thank you~" the insufferable showoff answered with a smug grin and a slight bow. Heiji scoffed and began to storm off to his room when Kaito interrupted. "Hey, Heiji? Do you want… lessons?"

"Lessons?"

"Acting lessons. To help you remember names better."

Well that was a very polite way to phrase it. He considered it for a moment. "…ya can do that?" Heiji finally asked, subdued and hopeful. "Ya really think ya can help me?"

"Of course! Just who do you think you're talking to?" he repeated, with that obnoxious KID-style grin that would definitely cause Heiji to forget the guy's real name again. "Now, do you have some relatively sound-proof room where we can practice?"

"Yeah, I got a makeshift movie room in the shed, just some bean bags an' a projector an' a mini-fridge. My parents made me insulate it cuz I like the volume real loud."

"That's perfect! Let's go!" And with that, Kaito grabbed his wrist and dragged him across the yard to the movie room, ignoring all his protests about whose house this was.

Once in the room, Kaito spent a few moments connecting his phone to the projector's Bluetooth port so that they could have some pictures to work with.

"Heh, is that seriously yer background photo?" Heiji teased when the projector finally came to life, displaying Kaito's phone screen across the entire wall. "What'd ya do, screenshot some random news article about him from two years ago? He's not even lookin' at the camera!"

"Well, what was I supposed to do?" he retorted sullenly. "I can't use a current picture of him without looking like a total creep!"

"Then why don't ya use one of the photos from when he's taken the temporary antidote?" Heiji asked, rolling his eyes to emphasize just how obvious the solution was.

Kaito blinked at him, his face entirely blank. The silence stretched. And stretched. Heiji frowned, wondering if he should explain what an 'antidote' was. Finally, Kaito tilted his head and asked in a calm, steady, natural tone, "...the what?"

"Ya know, the temporary antidote? As in, an antidote that's temporary?"

More silence. "…antidote. There's an antidote? You're telling me that he can get his normal body back?"

"Temporarily, yeah. It's only for like, a few days, or a few hours, or somethin'. It's not super consistent, to be honest."

Kaito bit his lip for a moment. "I… did not realize that was an option."

"Well, it is. The last time he took it was back when he rescued you outta that basement, remember?" Heiji answered. When he got no reply except more intense blank staring, he decided to clarify. "Ya know, when he dressed up as KID to make it look like you'd escaped?"

Kaito made a quiet strangled sound, then asked in a tone just slightly too high-pitched, "What? Wait, what?! Do you mean to tell me that he wore my suit?"

"How'd ya think he rescued ya, dummy?" Heiji shot back.

It seemed to take a few minutes for this information to finish processing, and then Kaito suddenly shot him a side look. "I don't suppose you have any pictures of that?"

"'Course I don't! I wasn't even in Tokyo that day! Nah, the most recent pictures I got of him with the antidote are from that school trip of his a few months back. But I did get some pretty good photos then, if I do say so myself."

"…send them to me."

"Hmph!" Heiji huffed in pride. For the first time all weekend, he finally had the upper hand! "Maybe I will, maybe I won't! Depends on how this name trainin' of yers goes."

"Heiji, my friend, prepare to become the absolute best person on the team at remembering undercover roles!"

Kaito turned toward the projector and opened his photo app to start setting up the exercise. Then he paused, looked over his shoulder, and corrected himself with a cheeky smirk, "Well, second best, anyway."

"Modest, aren't ya?" Heiji rolled his eyes.

"Alright, first step!" The display shifted to show a candid shot of Conan. "Who's that?" Kaito asked him cheerfully, pointing at the screen.

"Kudou," Heiji answered immediately. Then he yelped in pain. "Ow! What the hell?! When did ya put a shock collar on my wrist, and how do I get it off?"

"Now now, it's all part of the training! Carrot and stick. That's the stick. Try again!"

Kaito then walked him through a 'practice training drill' where Heiji was forced to repeat the name 'Conan-kun' over and over while staring at his picture, for what felt like entire minutes, until his mind had gone completely numb. Then he had to endlessly say 'Kudou' while looking at an older picture of the detective (also a screenshot from an old news article). They went back and forth a few times with this horrendously boring 'muscle memory' training. Then Kaito decided he was ready for some 'speed testing,' and told Heiji to blurt out the first thing that came to mind as soon as the pictures came up. He was skeptical, then absolutely floored when he actually got one right!

He was even more shocked to discover what the 'carrot' was.

He stared dumbly at the object in Kaito's outstretched hand for several long moments, before finally settling on a weak complaint. "But I don't even like gummy bears."

"Of course you do. Everyone does. They're gummy bears. And it's part of the training, so you have to eat it or else you'll never learn to get names right!"

"Why just one, though? What kind of psycho eats only one gummy bear at a time?"

"The kind that gets only one answer right! Again!"

Over and over and over again. It was horribly boring, and his wrist was starting to get sore. But after a while, the sensation of sugar on his tongue started to overpower the pain in his wrist, which was a really trippy way to measure progress, but hey, the important thing was that there was progress to measure!

They repeated the process with KID vs Kaito, and even Haibara vs Miyano for good measure. Sometimes it was photos, sometimes voices, sometimes both. Kaito started switching randomly between all six and even added in some strangers to throw him off. It was surprisingly exhausting work, and Heiji was desperate to take a break, but apparently that was the 'absolute best time to practice more.' It was awful.

—

Conan hadn't heard any updates from his friends since they'd gone to the police station, and he was starting to worry. They should've finished hours ago, which meant they should've resumed sending obnoxious selfies of both of them apparently competing to see who could make the most ridiculous face. But no, there had been no new photos for hours now! He tapped his fingers nervously on the desk, wondering if he should call.

It was bad enough that a mandatory school field trip on Saturday morning had prevented him from accompanying Kaito to Osaka. And though he technically should've been glad that his two good friends seemed to be getting along now, every additional update about the two of them having a blast together added to a strange weight he felt in the pit of his stomach that twisted and gnawed at him. He hadn't been able to eat anything all day because of it, and he was having a hard time focusing on anything else.

Finally he gave in and snatched up his phone and tapped Kaito's number. He resumed drumming his fingers on the desk while impatiently waiting for the call to go through.

"Hey babe, what's up?" Kaito greeted him, not sounding like he was in any danger at all. Oh, lovely. Just having a great time with his new best friend then. Conan wondered darkly what pet names he'd been using with Hattori, and shuddered at the thought. Yuck.

"Well, I was calling to ask how work was going, but from the background noise, I can tell that you're not working at all!" Conan scolded him.

"Aw, don't jump to conclusions, babe! First of all, it's totally ok to admit that you called just because you missed me and wanted to hear me call you 'babe.' Second of all, we actually are working right now!"

"Oh really?" Conan drawled sarcastically. He listened for a minute, cataloging all the noises he heard, then announced, "It sounds to me more like you're hitting each other with sticks in Hattori's backyard."

Bright, sunny, gorgeous laughter confirmed his deduction. "That's my brilliant Meitantei! You never cease to amaze me, my dear. Yes, Heiji is teaching me sword skills with some pieces of bamboo we found. That counts as work, right?"

"Does it?" he replied flatly, noting the first name basis with a twinge of something unpleasant in his chest.

"Ah, we're not in the backyard, though. We're on the roof."

"The… roof? You're on the roof of Hattori's two-story house?"

"Hey, he's teaching me sword skills, I'm teaching him agility; it's actually double work because we're so diligent and efficient!"

Conan sighed in exasperation. He really didn't want to hear about how much fun they were having without him. "Ok, I'm hanging—" he was cut off by a gasp and a shout, followed by a loud bang almost like a gunshot, then a terrible prolonged screeching sound like the scraping of metal, then a deafening horrible silence.

"Kaito?! Kaito! Kaito, are you there?! Are you ok?! What happened?! Answer me, Kaito! Kaito!" Conan leapt out of his chair and clutched his phone in a death grip, trying in vain to resist the wave of panic overtaking him. He continued uselessly shouting his friend's name until his phone buzzed with an incoming call from Hattori that he immediately accepted.

"What happened to Kaito?! Is he ok?"

"Oi oi, relax, will ya? Yer boyfriend's fine, he's just a massive klutz who dropped his phone down a rain gutter. He's tryin' to convince one of his birds to get it back for him now." There was some indignant shouting in the background about the difference between 'dropping' something and 'having it smacked out of your hand in an unfair move by a dirty little cheater,' but Conan was too relieved to be amused. He rubbed the back of his head and sighed deeply.

Belatedly, he remembered to correct Hattori. "Oi, don't refer to him as my boyfriend, Hattori."

"Eh? Why not?"

"Are you seriously even asking that?"

"Huh? …ah, right, it's cuz yer still little, so ya don't want people to know yer datin' a teenager, is that it?"

"Wow. You're hilarious. Don't call him my boyfriend. And help him get that cell phone out of the rain gutter; it probably has important data on it."

"Yeah yeah, talk to ya later, Conan-kun!"

Conan heard more muffled shouting from Kaito right before the call ended. He couldn't make out the words exactly, but he clearly heard Kaito say 'darling.' So he had been using pet names with Hattori! An uncontrollable shudder racked his body. That was SO gross.

Ug. There was that stomachache again. He shook his head and went to get some antacid tablets. He should go to bed early tonight to make sure he wasn't getting sick. He and Kaito had some training drills to do together tomorrow, and Conan couldn't afford to miss out on that just because of some lame stomachache.

Author's Notes:

Fun Fact: the hot sauce scene was inspired by a real life story of two guys I know who are, in fact, close friends and are both (supposedly) intelligent. Now, as for why someone with a master's degree in engineering would decide that a hot sauce chugging competition was a good idea, or why a genius Harvard graduate with a Phd in astrophysics would gladly accept said challenge, this is left as an exercise for the reader. If you figure it out, please do let me know.

Incidentally, the bamboo sword fight on the roof was also inspired by a true story involving that very same Harvard astrophysicist, who was NOT allowed to babysit small children again after that. (I will share the full story in the comments if anyone is interested.)

Oh, and remember a few chapters ago, when I talked a little too much about flamethrowers and the corresponding scars/dents/burns/damage around the house? Yup, same astrophysicist. That guy is kinda insane, and I love it.

The next chapter will be from Conan's perspective to watch as Kaito fulfills a lifelong dream that he's had for nearly four or five whole weeks now: to appear on national television for a full-length interview.