AN: So I decided to compile all of my future genshin fics into this one story, just to save some time and space on my part. Hope you all enjoy!

Mika was far from the confident type. Ever since joining the Knights of Favonious, he realized that what little self esteem he had seemed to diminish every time he was in the presence of the other knights, especially those with a higher rank than himself. It had gotten to a point where he could hardly hold a conversation with them outside of their usual work communications, much to the dismay of his older brother, Hoffman. He had hoped that Mika joining the knights as a cartographer would give him a bit of a boost in confidence, but the more he interacted with the other knights, the more clear it became that he was nervous around them.

Kaeya was one of the first knights to try reaching out to Mika. Most of the other knights had just accepted that he was the shy type and would eventually warm up to them. Kaeya wasn't keen on doing the same thing. He was a social butterfly at heart, and he couldn't help but look at him the way he looked at Noel, Bennett, or Razor, as a kid with a lot of skills, but could really use a friend. His first time interacting with Mika resulted in mostly nervous responses to his questions, so he tried joking around like he normally would with friends. This seemed to only make the situation more tense as Mika forced a smile. After that, Kaeya was determined to get the kid to loosen up a little bit. It would do him no good as a Knight of Favonius to constantly be tense when talking to his own co-workers, especially if he couldn't communicate with superiors without stuttering.

Hoffman was the first person he turned to to get advice on how he should get to know Mika better. Who better to ask than the big brother himself? Hoffman was extremely grateful that another knight wanted to make Mika feel more welcome and comfortable among their ranks. He was always worried that he would have trouble coming out of his shell, but at the same time he didn't want to baby him. Mika was an extremely independent person; self reliable, sufficient, and would probably be annoyed if Hoffman was constantly trying to get him to socialize. He had grown up much faster than Hoffman liked though, and even self-sufficient people need friends to rely on.

Hoffman's advice was for Kaeya to try and teach him something. Mika was always willing to learn new things and seemed to be the most relaxed when he was actively learning. Kaeya suggested some combat training, as long as he was willing to accept. Seeing as Kaeya was not only a master swordsman but a cryo user as well, Hoffman thought there would be no better person to train him.

So, with some help from Hoffman, he managed to convince Mika to join him for some one on one training. He had limited experience training with his pole arm, only learning the bare essentials to defend himself in the field, and although he was still unsure about personal training from Kaeya, he figured that if Hoffman trusted him that he should too.

That didn't make the start of the training session any less awkward. Besides the two of them, the training yard was completely empty. Kaeya had known he would probably get nervous training around other knights, so he tried to pick a time when there would least likely be anyone else training. Even though they were alone, Mika still appeared stiff and nervous as he and Kaeya went through some basic exercises on training dummies.

"Alright, let's take a quick water break." Kaeya said, noticing that Mika was starting to break a sweat. The sun was high in the sky and the day was hot, so hydration would be important.

Mika just nodded in response as he laid down his spear, walking over to the bench where he left his belongings. Kaeya had hoped by now that he would have said something, but the only response he ever got from him was the occasional single word answers to his questions. Perhaps a break would be the perfect time to make small talk.

"You're doing well," He stated as he took a swig of water from his own bottle. "Have you had any combat training before?"

"Oh, not really." Mika said as he set down his water. "Just some defense training."

Not exactly the conversation Kaeya was looking for. It seemed it would be no use trying to force a conversation. He would just have to hope that he would become more talkative as the training continued.

"Well then, how about we do some hands-on combat. No weapons, just basic grappling."

Mika seemed unsure of himself, but nodded in agreement anyway. He stood up to continue the lesson, and he and Kaeya walked to the middle of the training grounds.

"Alright," Kaeya stated as he got into a starting stance, "let's go over some basic grabs and pins. If someone bigger than you tries to take you down, you have to use their momentum against them."

He copied Kaeya's stance and held it, his body stiff as a board.

"You should relax, kid." He chuckled. "Being tense will limit your movements."

"Oh, sorry." Mika responded, a small blush of embarrassment on his face.

"Here, come at me and try to grab on. I'll show you how to counter."

Mika walked over to him, looking a bit confused.

"Here, just try to grab my hands."

"Okay, I'll try- HEY!" He shouted in response as Kaeya suddenly grabbed onto his shoulder and pushed him to the side as he moved.

"Like I said, your tense. Loosen up a bit."

Again, Mika flushed pink. "S-sorry captain."

Kaeya sighed as he released his defensive stance.

"Here, let me just show you where to grab if you're on the offensive." He approached Mika, now in a defensive stance.

"If you're trying to take someone down, just put one hand on the shoulder, and one hand on the side-" He suddenly stopped as he noticed the boy flinch once his hand made contact.

"Is something wrong? You aren't injured are you?"

Mika's eyes widened. "N-no! I just- was surprised!"

Kaeya couldn't hide his smirk as he formulated a new plan to get Mika to lighten up a bit.

"Okay, well like I was saying, just put your other hand on the side. Just like this-"

Instead of resting his hand, he squeezed at his side suddenly. Mika nearly jumped, a quick and startled laugh escaping him. It brought Kaeya back to the days where he would tickle Diluc. He solemnly got the chance to launch tickle attacks on his brother now, but that didn't mean that he had forgotten his skills as a certified tickle monster.

"You know," Kaeya said with a mischievous grin, "whenever I think my high strung brother needs to loosen up a bit, I've found there's one guaranteed way to get him to laugh."

Mika's eyes flashed with a sudden look of excitement. Or fear. He couldn't really tell at the moment. The only thing he knew was what was about to happen. He was no stranger to brotherly mischief, which included Hoffman tickling him in the morning to wake him up, or to get him to stop reading and come to dinner. Kaeya had the same look in his eyes that Hoffman had whenever he was in the mood to make his brother laugh, and that meant trouble.

"S-sir Kaeya, let's talk about this." Mika stuttered, a grin already starting to appear on his face.

"Sometimes talk can only get you so far." Kaeya responded, wiggling his fingers in his direction. "And sometimes the best way to get someone to finally relax is to make them laugh. I can't think of a better time to do that than now."

Even though he meant it, he still looked for any sign that Mika was uncomfortable. After all, the last thing he wanted to do was scare him off. Luckily, Hoffman had relayed some rather useful information to him while gushing about how cute his little brother was: Mika, on occasion, enjoyed a visit from the tickle monster. Whenever he wasn't in the mood for a visit though, he would let him know. Now, as his wiggling fingers grew closer, Mika simply closed his eyes with a huge smile plastered on his face, seemingly bracing himself for what was about to happen, the same thing Diluc would do as he braced himself for one of Kaeya's tickle attacks. In the moment, Kaeya felt the same playfulness he did when he and his own brother were kids, and in an instant he finally brought his hands down to Mika's sides.

Mika nearly screamed as he felt the sudden jolt of hands squeezing at his sides. He couldn't hold back his laughter for a moment as he immediately buckled at the knees, bringing his arms down to protect his sides as the ticklish sensations sent shockwaves through him.

"Sir Kahahahaeya!" He cackled like mad, falling farther to the ground to try and curl up into a ball.

"What is it?" Kayea teased, knowing fully well what he was doing.

"Nohohot there! It tihihickles!"

"It tickles?" He quipped, "I would have never guessed."

Mika's eyes squinted as he continued giggling.

"Nohohot the sides! Plehehease!"

Apparently this was a sweet spot on him, it was clear from the way he shook his head back and forth, trying to roll away from the dreaded tickling fingers, only for them to attack his other side.

"Not the sides," Kayea chuckled in response. "Well then, how about... here!"

Kayes hands suddenly moved to Mika's underarms, which were left vulnerable as he tried to protect his sides from the vicious attack. Mika's laughter only seemed to increase as he now trapped the calvary captain's hands as he clamped his arms down.

"You know, I'd say this is good training." Kaeya joked. "You're working on stamina and resistance against interrogation, all kinds of exercises useful to knights."

"Nohohoho one is gohohohoing to tihihihickle me in the fheheheild!" Mika's face began flushing a bright pink as his nose scrunched up.

"You never know." Kaeya sang as he continued wiggling his fingers. "The enemy could find out how ticklish you are and use it against you! A knight has to be prepared for any situation."

"Thahahahahahat's so duhuhumb!"

Kaeya was almost shocked by his statement. This was the first time Mika had the guts to call something Kaeya said dumb. He was sort of proud in a way, but he also couldn't let anyone get away with that, even if what he said was a joke.

"Oh, I don't think it's dumb. If you aren't careful, a tickle monster out in the field could find you and- get you!"

As he finished the statement, he suddenly freed his hands and started scribbling along his tummy. He seemed to have hit the jackpot, as Mika let out a squeal louder than ever before.

"NOHOHOHOH, NOT THERE!" He screeched.

"Not here?" Kayea couldn't help but start laughing along with the hysterical boy. "You said that about your sides. Are you just a walking tickle spot?"

He wasn't sure what was worse: the torturous fingers scribbling under his arms or the constant teasing the cavalry captain uttered as he tickled him. Mika somehow flushed an even darker red at the statement, but didn't bother trying to respond as he continued his giggling. Instead of kicking and thrashing to escape, which was what Kaeya was used to from tickling his own brother, Mika seemed to just curl even further into a ball, despite the fact that it wasn't providing much protection. He was like a pill bug curling up into a ball to hide, a very ticklish pill bug at that.

It was a nice feeling, being able to finally let go of his anxieties. It had been so long since Mika let himself laugh like this. Even though he didn't really have a choice in the matter, he felt a kind of relief wash over him as he uncontrollably giggled. It was like all the tension and nervousness that had been building up inside him was released and replaced with laughter. It brought him back to a time when Hoffman took care of him. He would tickle him just like this whenever he was feeling sad. In the moment, Mika couldn't help but feel that same brotherly closeness with Kaeya.

He rolled back and forth, desperately trying to escape the wiggling fingers, all the while cackling as one of his worst spots was targeted. It was like he somehow knew where he was most ticklish (another piece of information Hoffman may or may not have told him), and the constant changing of where he was tickling, upper stomach, lower stomach, back to the sides, was driving him mad.

"YOUHOHOHO'RE THE WOHOHOHORST!" Mika squealed, snorting at the end of the statement.

Kaeya couldn't help but laugh along with him. He could only hope that Mika wouldn't be embarrassed. His laughter was contagious however, and he didn't try to hold back his own giggling with every snort.

All good things had to come to an end, unfortunately. Mika could only handle his brother's tickly onslaughts for so long, and it seemed his tolerance for it hadn't improved much.

"OHOHKAY! TIME OUT!" He shouted.

Kaeya took that to mean that he was truly at his limit. Even though he was having fun with all this, he decided it would be best to show some mercy on the poor boy. He chuckled to himself as he released him from his clutches.

"I'd say you're even worse than my brother." He smirked as he looked down at Mika, still rolled up in a protective ball, giggling uncontrollably.

"Whahahas that really necessary?" He asked, finally lifting his head up and letting down his defenses.

"More than necessary. I think a little bit of laughter can do anyone good." Kaeya reached a hand out to help him up. After regaining his composure, Mika took it and got to his feet.

"Easy for you to say," He said with a pout.

Again, Kaeya laughed. "Look who's finally loosened up a bit. You're now confident enough to insult me, so I'd say that's a big improvement!"

Mika, stunned for a moment, gave a huff of amusement. "There are other ways you could have done that."

Kaeya raised an eyebrow. "Oh really? Because I feel like I tried everything else. Is it that you wanted me to resort to this method?"

Again, a blush crept up on his face. He definitely had fun, but there was no way he was ready to admit that to the cavalry captain. He had made good progress that day, but he would need a few more training sessions before he was ready to say something like that.

Kaeya smirked knowingly. This was already such a leap from the nervous boy he had started training with. He had a feeling that Mika would be a lot more receptive to training now.

"Well," he said, a sly grin still on his face, "I guess I'm just glad I was finally able to break the ice..."

Mika took a minute to register the fact that the statement was a cryo pun. He groaned as the realization dawned on him.

"Alright, now THAT was the worst."

Kaeya felt a sense of pride at that, both for the pun and for the fact that Mika was still in the mood to banter with him. He chuckled as he gestured to the center of the training grounds.

"How about we finish up this training session?"

Mika smiled, already running ahead.

The rest of their training day was successful, though Kaeya refrained from utilizing tickling as a form of combat. However, he had a feeling this wouldn't be their last training session.