Resolve. By literal definition it was the determination to do or achieve something. Like all abstract notions, resolve was relative, subjective and immaterial. Asking to prove his resolve was like asking to prove his love to Usagi, or his devotion to helping people as a doctor.

Mamoru pinched the bridge of his nose. It wasn't that he didn't appreciate the 'help' from Acheron, trying to make it easier for him. The additional condition was welcome – it made Mamoru feel like Acheron was also trying to meet him, on the other end.

But as Helios had said, the other guardian's intents were rather mystifying. Prove his resolve? In what? And how?

How would he prove his love for Usagi? Tell her, every day. Show her, with everything that he had. He didn't know how to not love her, and everything that he did in his life when she was around was simply that – an extension of what filled him. His love for Usagi just permeated him, so that it was like his blood ran with his love for her, and there was always a bond to her to his heart and soul.

How would he prove his devotion as a doctor? He had studied, he had earned his degree, and he practiced as a doctor. He cared for his patients, he saw them as the people that they were, and he prayed their health would be strong and carry them to happy lives.

And, three days before Hotaru's message, Mamoru and other doctors had been given a pamphlet at a presentation. A few of his colleagues had thrown theirs away, after it was over, not giving the organization more thoughts because they had no intentions on putting their lives through radical changes. He would have done the same, but something about the thin bindings of paper with basic information had caught his eye, and in the end Mamoru tucked it into his pocket and brought it home, where it stayed on his desk. Such a small thing, but constantly drawing his thoughts to it.

Because he did want to, and the only reason he didn't put it on the list of things that were realistically something he would do was because it would mean being away from Usagi for long periods of time.

Was the timing of the guardian's words a coincidence? Or a sign that he should look at it again?

Resolve.

Mamoru leaned back in his seat and exhaled deeply. He knew Acheron had kept an eye on him for a long time, and he said now that he would know if Mamoru was able to prove his resolve.

A guardian who had lived for centuries, upholding the balance of the world. Even in the present time he travelled the globe, keeping busy. Obviously, Acheron did not trust him enough because Mamoru had not proven himself – or, there was still something he was missing, something he wasn't doing right that kept the guardian busy.

Did the guardian think him pathetic? Mamoru wondered, the doubt that had been planted since Acheron rejected meeting him in person now deeper and darker in his heart. For a prince of Earth to be isolated in one small country, away from the rest of the world.

Japan was a secluded nation, historically isolated due to its geography and culture. It wasn't legally closed off like some nations were in the present times, not physically with the technological advancements in travel, and yet culturally, the society tended to be exclusive to the rest of the world.

Acheron wanted him to remember, or to prove his resolve. He needed to remember his life as a prince of Terra – then, by extrapolation, he needed to prove his resolve as a prince of Terra.

Mamoru reached for the pamphlet.

"Doctors Beyond Borders," he read the letters on the front page aloud, and then opened its pages to the section on how to apply.

It was a weird day.

Wait, no, that made it sound like he didn't have weird days, and that was a statement that couldn't be further from the truth if he tried, so Tsuna supposed the correct thing to say would be that it was a weirder day than usual. Whenever she saw him Bianchi turned completely still, as if she was playing dead. Lambo was playing hide-and-seek by himself instead of bothering anyone. And just now, Haru nearly shrieked and all but ran away from him before he could say a word.

Tsuna patted his face, wondering if someone – Reborn – had written something on his forehead or put a mask on him. It didn't feel like there was anything on his face, but it was Reborn, so.

"Tsuna-san?"

Tsuna snatched his hand away from his face and turned around. Hotaru stood there, with a curious look and nothing else – no freezing up, no crying out that she was busy and bolting in the other direction, no suspicious behaviour in any way. It was such a normal reaction that it almost felt abnormal today. The only thing remotely unusual about her was the violin case she was carrying.

"Are you shopping for Reborn's birthday gift as well?" she asked before he could ask what brought her here.

Tsuna's mind froze up. "Reborn's birthday?"

Hotaru nodded. "Takeshi told me it was today, and gave me an invitation to his party saying Reborn wanted me there too. Is it okay?" she added, tucking a lock of hair behind her ear. "I was told it would be at your home."

Of course it would be. But more importantly – it was Reborn's birthday? Today?

"Today?!" he shrieked.

A part of his head that wasn't frozen up at the idea of Reborn having something as normal as a birthday remembered that it was his own birthday tomorrow.

Which was great and all, but more importantly, Reborn's birthday. Today. Which he had not known about, and likely would receive his wrath for even though no one until Hotaru had seen fit to tell him about. Ignorance was no excuse for Reborn.

A little disappointed and a lot terrified, Tsuna clutched at his head. He was going to be murdered on the day before his own birthday for the crime of forgetting an evil baby's, what was his life even.

"I'm going to take that as a no," Hotaru said, reading his answer from his panicked response. "Do you want to come with me? Takeshi said that Reborn was alright with a violin performance," she gestured at the case she was carrying. "But that didn't feel like enough of a gift, so I was going to grab something else as well. I wasn't sure what to get him, but you know him better than I do. We can pick a gift together."

In that moment, Tsuna swore that he saw halos and wings shining with divine light behind Tomoe Hotaru, who was clearly an angel sent from above to save him from Reborn.

On their way to the shopping district, the conversation turned from what Reborn might like to a discussion about zodiacs. Tsuna ended up telling Hotaru that his birthday was tomorrow and flushed a little doing so. It felt a little like a demand that Hotaru do something for his birthday, and that just made him feel like a shameless bastard. Luckily for him Hotaru only nodded coolly at that revelation, sparing him a lot of embarrassment.

"You're both Libras," Hotaru said as they walked down the street. "Under the protection of Venus, the planet of love, beauty and metal."

"I didn't know you were interested in astrology," Tsuna wondered. She didn't seem the type to be looking into daily fortunes based on star signs. She was mostly normal.

Hotaru smiled. It was a secretive smile, almost impish, and Tsuna threw his preconceptions into the trash. She had a playful side, too, it looked like.

"I like celestial objects," she said, like it was an inside joke. "It's a good planet to be protected by – they all are, really, if you get to know them."

"I guess," he said, even though he didn't know all that much about astrology. He hadn't even known he was a Libra, or that he was protected by Venus. It was nice to hear that it was a good planet, since he was a bit far from love and beauty. Metal, maybe, thanks to Reborn and his trigger-happy tendencies.

If he really was protected by the planet of love, he could be using some help with Kyoko.

"Which one are you?" Tsuna asked, curious. He didn't know her birthday, and if she ever invited him over for a party – probably along with Yamamoto – he didn't want to be caught off-guard like he was today. Hotaru probably wouldn't react like Reborn, but Reborn would probably say something like how a mafia boss treated ladies properly and forgetting their birthdays was a crime punishable by death in the Vongola.

That was actually so likely that it made chills crawl up his spine at the very thought.

"My birthday is January sixth, so I'm a Capricorn," she explained for his benefit, since he had no way of telling what date fell into what astrological sign. "Protected by Saturn."

He knew enough to know that was one of the planets in the solar system, and that was about it. "Um, planet of-" dirt? ". . . earth?"

"Good guess," she praised. "But no. The planet of silence and destruction and rebirth."

Tsuna nearly tripped over his own feet. That didn't sound like a good planet to be protected by?! Unless being born under that planet's protection meant immunity to whatever it was planet of – in which case he was screwed. Saved from Reborn and his trigger-happy tendencies, maybe, but with a very bleak future ahead of him.

"It's not all bad," Hotaru assured him when he failed to keep a proper poker face. "Sometimes you can't have hope and rebirth without starting over."

"I guess." Still, a little scary, what with 'destruction' being a thing. "What about Yamamoto-kun?"

"He's a Taurus. So is Haru, by the way. Taurus is also under Venus," she added. "You three have that in common."

And little else, Tsuna thought, but held his tongue.

The first shop they stopped at was the bookstore. Hotaru looked over the fairy tale books with a thoughtful eye, and Tsuna had to stop her lest she be murdered by Reborn for buying such a gift. The books that would be more to Reborn's tastes . . .

Would be mafia-related books, which he'd probably already know like the back of his hand.

Tsuna despaired.

"Maybe not books," he suggested weakly.

Hotaru gamely agreed to his suggestion.

"I mean, we could get a certificate to La Namimorine," she said. "But that seems a little thoughtless, like we didn't put much consideration into it, so I'm thinking of it as a last resort."

"I guess," he said, not exactly the best at coming up with gift ideas but seeing her point. It literally put the value of the gift on what was given, and Tsuna didn't really have money.

"What does he like?" Hotaru asked, peering into the shop window for baby clothes. She seemed to be interested in the pink, frilly dress that was exactly Reborn's size, and Tsuna was reminded that like most of the people in his life, even Tomoe Hotaru, for all that she appeared normal, sometimes wasn't.

At least she didn't bring violence and unnecessary trouble into his life like certain other people.

"Um," Tsuna said. How did one say, 'be sadistic towards a student in the hopes of making him a mafia boss'? Reborn's lessons didn't cover this aspect without pulling the person into the Vongola, which he had no intention of doing in the first place.

What else did Reborn like? Shooting Tsuna. Sadistically making Tsuna suffer. Mama's cooking. Espresso.

That last one might have had a chance.

"Espresso?" he ended the word with a lilt upwards, so that it came out sounding like a question. A better question to ask in general might have been why Tsuna was making the effort to get a gift to the guy putting him through all this torture.

Dumb question, Tsuna knew. For all that Reborn put him through, his coming into Tsuna's life had given it a vibrancy he hadn't even dreamed of.

At the very least, a gift was necessary if only to thank his tutor for bringing the good things into his life.

But seriously – what did Reborn like? What did he like, that Tsuna could get him? Tools? He had Leon – and given that he used anything and everything to put him through torture, Tsuna wasn't sure if he wanted to give him things that would contribute to his pain and suffering.

"That can't be good for someone of his size," Hotaru mumbled, pondering his answer out loud, and Tsuna clapped a hand over his mouth. "He won't grow if he keeps drinking coffee at that age."

Torn between the urge to laugh and tremble in fear, Tsuna shook a little.

"How about espresso cups?" Hotaru suggested, pointing to a shop that sold dishes, from what he could see. Having never been to that shop, Tsuna shrugged and followed her in.

And then promptly regretted it when he saw the price tags. "Um, Hotaru-san."

Those were not price ranges that normal middle school kids could work with. Why were dishes so expensive? They were dishes. He broke a lot of them when he was younger, and with Lambo and Bianchi and Reborn living in his house they broke a lot of dishes on a regular basis. Were all plates, bowls and dishes this expensive?

He tried to calculate how much that all was and felt himself grow faint.

"Oh, these are cute," Hotaru exclaimed quietly, making a small gesture to a set with seven cups and matching saucers that came in the color of the rainbow. She didn't even glance at the prices.

Tsuna, who took more than a glance at the price tag for the set, had to bite down a shriek. Seven small cups that could barely fit a few gulps, combined, and the price was too high for it.

"Aren't you too young to be drinking espressos?" asked the lady, a stern, maternal woman, sweeping in with eyes glinting behind her glasses. It was a talent of sorts, to have words worried about health be spoken in such a scary manner.

Hotaru, though, didn't even look phased. "It's a gift for someone who really likes espressos," she reassured the shopkeeper, wisely not bringing up the fact that it was a gift for a baby.

The lady nodded imperiously. "I suppose it's fine then. Do you want me to wrap these?"

"Yes please," Hotaru said before Tsuna could suggest they reconsider. She paid for it at the register without batting an eye at the high cost, and gift in hand, came back.

"There," she said. "Now we have a gift."

We, plural. Tsuna knew what she meant by that.

"Hotaru-san," he protested, but she waved him off and made him hold the package.

"I wouldn't have known to get these if you hadn't told me," she argued. "Besides, I'm tired, Tsuna-san. I had to attend the history club early this morning, I'm not up for further shopping while carrying my violin around with me."

She did look a little tired, now that she mentioned it, so Tsuna didn't argue further and carried the package.

"But next time," he said, unable to not protest entirely.

Hotaru looked satisfied by his answer. Unlike Reborn's satisfied looks, she just looked genuinely happy, and Tsuna didn't feel a chill crawl up his spine at the sight of it. "That's fine with me."

"I know you said I could just play the violin," Hotaru said, when her turn came up in the ridiculous event Reborn called a Vongolian Birthday Party. She, like Yamamoto, took the threat of death as the penalty for the lowest scoring as a joke. Tsuna wished. "But I also picked up something with Tsuna-san."

Reborn raised an eyebrow and Tsuna did his best to not make eye contact. The theory that Hotaru was an angel sent to save him was starting to gain legitimacy, though, because Reborn didn't start shooting at him immediately.

When their joint gift – the news made Gokudera flail and surprised Yamamoto – was revealed to Reborn, the baby fell silent.

Tsuna, recognizing that to be a Not Good sign, squirmed while Hotaru looked puzzled.

"Do you not like it?" she asked, able to be brave because she didn't know about Reborn's true personality.

Bianchi, frowning, crossed her arms over her chest. "Who chose this?"

"I did," Hotaru said, still looking bemused. "We went to get espresso cups at Tsuna-san's suggestion, and initially I wanted to grab the plain white ones because you can't really go wrong with classics, but then the rainbow-colored ones were so cute I had to grab them."

She dug out the receipt from her pocket, neatly folded. "If you want you can go get it exchanged. I checked their store policy."

Tsuna hadn't even known there was a policy like that, let alone noticed her checking it.

"It's fine," Reborn said shortly. "Seventy-five."

Hotaru nodded at their score and opened her case to take out the violin, but Tsuna couldn't help but remember just how Reborn had frozen at the gift.

For a split second, he had been – mad? Sad? Defensive?

A strong mix of emotions he hadn't been able to define before it was covered up.

With the violin tucked beneath her chin and the bow in the other hand, Hotaru looked at Reborn. "Do you have any requests?"

Reborn leaned in, looking interested while Tsuna sighed in relief.

Well, but he shouldn't have worried about it. His tutor was a lot nicer to the girls. If Tsuna had ever given Reborn something like Haru's gift, he would have been shot once for every target on the outfit to let him experience the 'thrill'. As for Hotaru, Reborn had been willing to not only accept a violin performance as a gift but told her through Yamamoto about it in advance.

"Any jazz songs?"

Hotaru pondered the vague request for a moment before she raised the bow to her violin. "Is 'Fly Me to the Moon' okay?"

"That's fine with me," Reborn said. Hotaru nodded, and began to play.

In all honesty, Tsuna didn't have much of an opinion about violins. He once went to a recital with his mom, and vaguely remembered thinking that the kid performing on stage made the violin sound like a tortured cat. He was hardly musical himself so maybe that was an unfair assessment, but still. Tortured cat.

It was only when he heard Hotaru play now that Tsuna realized the violin was an instrument. As in, something that made music people actually liked to listen to. Not tortured cat sounds.

In the right hands – in hands that knew what they were doing – the results were the furthest thing from a horrible screeching noise. Sound flowed like water, smooth and pleasant to even his ears. Tsuna understood now why people paid a lot of money for expensive lessons or went to concerts to listen to orchestras.

It looked like everyone was enraptured, as if the music had grabbed them all with hands he couldn't see, only hear, and wouldn't let go.

She wasn't even looking at any sheets – it was all just memory, but her movements were smooth, and the bow moved back and forth on the strings while her fingers danced on the slender neck of the violin, coaxing forth a sound that reminded Tsuna, weird as it was, of chocolate. Smooth, rich, entrancing – but for his ear, not his tongue.

Almost too soon, the song came to an end. Hotaru lowered the violin and bow, and gave a small curtsey as Haru – and everyone else – started applauding. Tsuna snapped out of the daze he was in to clap as well.

"A fantastic rendition," praised Reborn. "A solid ninety-five."

Hotaru laughed quietly. "You're too kind."

For once Tsuna actually agreed with Reborn's assessment, because it had been a great performance. And once again, she truly had to be an angel because instead of just sticking to the violin performance, she also brought him along to buy a gift for Reborn.

Maybe this day wouldn't end with the usual hectic shenanigans.

Then Lambo brought out his own gift – something he called a Lambo stick that had no purpose – and predictably, the day ended in the usual fiasco. Lambo cried and threw the grenades he pulled out from his hair, Gokudera shouted and added to the ruckus despite his best efforts, Yamamoto laughed because he still saw it all as a game even as he gently pushed the girls out of danger's way and Reborn, because he was Reborn, came out of it completely unscathed.

As for Tsuna, he ended up spending his thirteenth birthday in the hospital.

AN: Updating early since I plan on updating this Thursday as well so what's a few hours.

I'm quite partial to Masa Golob's violin cover of 'Fly Me to the Moon' but if you have a favorite of your own you do you.

Also since a few people asked if Mamoru was going to go through a boot camp like Hotaru did, I figured I should first send him away from home to suffer a bit in true Petrichor tradition (readers: Huinari where is your logic).

Kawahira's reaction to Mamoru's thoughts and choice would go a little like this -

In an alternate world where Acheron has a positive opinion of Mamoru: …well, his heart's in the right place… I better make sure he's not in danger.

In an alternate world where Acheron is neutral towards Mamoru: Eh, not a bad idea. Good luck.

In Petrichor, where Acheron dislikes Mamoru for Reasons: *Deep, Frustrated Sigh* I hate this man and the fact that technically I live for him.

Sweet Dreams~