Everyone was geared up and ready to take on the mad god that pissed them off, but then a phone call just rang. All eyes turned into the only tech guy, who possibly would bring a communicator with him despite the securities and confidentialities.

Tony Stark, for his part, unusually paled and he immediately brought his phone out.

A tense silence surrounded the adults when the a very calm and young voice spoke, "Tony-san."

Natasha perked up at the unmistaken Japanese dialect with narrowing eyes. She had spied for the young CEO some time ago and she had never heard this voice before. The usage of a first name also bugged her because she knew that in Japan, it indicated a closeness yet Tony never collaborated with any Japanese businessmen in her undercover nor did any indication that he had business partners in that country.

The voice was also relatively young, almost like a teenager just near adulthood. Maybe, the person on the line was around in their early twenties. How someone young would just call the billionaire familiarly ad even make the latter pale was suspicious. The reason for the call was even more suspicious because of the timely coincidence.

Sharing a glance with Fury, they both decided to tackle the uneasy information later when Loki was captured.

"Hey, Cielo! Nice weather we're having—" people should give props to how innocent and genuine Tony sounded as if he really was just having a normal day despite everything and their current situation.

Steve glanced at the nervous man, surprised that to see his confidence gone. Clint wondered if they should leave the man to pacify his caller first because Thor looked too impatient from the interruption. They really did need to hurry and catch the god of lies.

"Tony-san," the voice said again. This time, it was firmer and more masculine yet still held its youthfulness. The person—probably a young man at 20—carried this calmness in his delivery but there was also tough steel in them.

"You're grounded."

Everyone stared blankly, wondering if they just heard it right. They couldn't believe their ears.

And Tony? He just cursed. He's so screwed. Why did he get involve with the SHIELD's business again?

-0-

Sawada Tsunayoshi felt his intuition warning him of his troublesome lightning and when the television broadcasted a so-called god terrorizing New York, he immediately put the two together.

After ending his call to Tony—that's totally one-sided and probably terrifying for the older Lighting—the brunet hopped on his jet plane with his guardians and advisers and promptly travelled to New York.

The place was crawling with brutal monsters and Reborn, the freaking sadist, proposed a kill count competition the moment they arrived. His guardians all expressed their highly competitive selves, even cute and sweet Chrome and immediately started attacking the 'aliens'.

(If he's not mistaken, Reborn's winning by a long shot but that's mostly because he's stealing all the other's prey.)

Tsuna would normally discourage them. They still needed to keep a low profile. But he had other priorities and New York's getting destroyed by these monsters so defeating was fine.

"Tony-san," he called out to the man in the red iron suit. His second Lightning Guardian let out a nervous chuckle and raised his arms in surrender, "Can I plead for fifth here? It's SHIELD's fault!"

Honey-brown eyes narrowed, flashing hints of orange hues. "Grounded for three months. No gadgets or Pepper-san for those months," he continued firmly and strictly.

Ignoring the whines and retorts from the manchild (Reborn had a field day when despite being much older, Tony was just as bratty as Lambo), Tsuna walked to the blue man with a shield. His intuition told him that this person was the likely 'leader' of the Avenger so he would talk to this man.

"Hello, Mr. Shield Man. My name is Tsunayoshi Sawada, Tony's legal guardian," he smiled warmly before his smile turned sharp. "Please explain why my ward is involved with a group that I am not informed of."

The Avenger, excluding Tony for obvious reasons, froze and stared unblinkingly at the young teenager in front of them. The ongoing alien invasion was one thing, although some unknown individual seemed to be fighting them while this went on. This 'Tsunayoshi' looked old enough to be Tony's son but apparently, it's the other way around. Then, there was even the previous interaction from the two.

It's really not a good day for anyone. Maybe, except for the Vongola.


Bonus:

- Tony and Lambo are both bratty Lightnings and do not get along at all. Lambo, especially, is pegged that an 'old man' is replacing his guardian spot. Tony just can't believe he's sharing the same role with a child when it's obviously better with just him (his words, not Tsuna's).

- Reborn finds it ironic that Tsuna, who's barely an adulthood, is more mature than Tony, who's supposed to be New York's hero. It's funnier because Tsuna actually does baby Tony because of the man's unhealthy habits.

- Gokudera and Tony do not get along (might have to do with their flames) and messing with him is the only other time Lambo and Tony agrees with each other. Protecting the family is the first.

- Tsuna ships Pepper and Tony together and subtly tries to matchmake the two. Because of Reborn's teaching, his methods are not that normal…but it's producing results so it's fine.

- After Loki is captured but before they let Thor drag him back to their home, Tsuna absentmindedly wonder how much control the god has or if he's completely mindcontrolled. This sets up a way different event afterwards.

- Also, SHIELD finds out the hard way why no one should mess with a Vongola, even if it's Tony. Tsuna can hold grudge really hard and gets back on people, who hurt his precious people.

- Hydra is completely massacred.


A/N: I didn't write how Tsuna and Tony meet, but I have many ideas like Tsuna's first try on being a Vongola Decimo and having a business party which have Tony in it or Tsuna finding an injured Tony and healing him. I wanted to write the Avenger's reaction instead so I went with this. Anyway, I love the idea of Tony adopting kids (or teenagers) like Spiderman but I have this idea of Tsuna adopting him instead. It's funnier because of the irony that Tsuna is the legal guardian instead of the other way around.