Well this isn't unnatural at all!

Verde's Conclusion

"What do you mean my flame was tampered!?" Tsuna shrieked as a needle almost poked him in the arm again.

"It's as I said, your flame was once tampered with, if my calculations are correct, when you were approximately five years of age." Verde pushed his glasses up and stared in fascination at the results that he held in his hands.

"HIE?!" Tsuna squeaked. Reborn started to ran his fingers up and down on his beard (when did he get that!?).

"Ah, I see." Reborn acknowledge and nodded his head. "Tsuna's flame somehow got unstable and in order to stabilise it again, his flames acted up and kept on swallowing flames that it came in contact with, am I correct?" Verde nodded. "And because of Dame-Tsuna's luck, his flames adopted too well to the different characteristics of the other elements and his flames somehow copied the flames it kept in contact with when the seal was broken."

Verde hummed and took out a clipboard and a pen and wrote something down (Tsuna did not need his intuition to know it was about him)."That is correct."

His eyes glimmered. "Your Sky Flames fascinates me so I shall examine it more." and as he said those words, he took something out of his left pocket and stabbed Tsuna in his right shoulder. The two were expecting blood but not actual Sky Flames to sppear in its tube.

"What is that!?" Tsuna shrieked.

"An invention I created a few years ago."

"Why did you even make that?!"

"For science, of course."

Tsuna deadpanned: "You are the literal saying of that..."

(Reborn mentally sighed in relief as images of his student in a tube disappeared. That was...unsettling...)

====
A/N:

Well here you go! The answers to why Tsuna can mimick flames and I still don't know how I even thought of this... AU..? I guess it's an AU... Somehow..

I guess you can say this is the end or something. But I'll probably add some random shots if I get bore or something. So maybe not?

Tsuna: You are very unsure.

Me: You don't know the half of it.

Reborn: Congratulations on getting rank one from the #helpmeeeee tag.

Me: I can hear sarcasm in that.

Tsuna: What kinda rank is that?

Me: Beats me but hey, I got first in it.