One day in Green Hill Zone, Sonic is having a walk on his way home, when suddenly, a random letter floated from out of nowhere and landed on his face. Then he decided to take a look at it to read it. The letter said:
"If you wanna win some gold and stuff, why not heading to my house to see what happens? - Heartina R."
This is too sick, he thought, but that's okay; I gotta see if Heartina is in there. And so, Sonic immediately rushed to what appears to be Heartina's house.

Once he got there, Sonic saw a some paintings of cheery blossom flowers around Heartina's house. Then he took a deep breath and went inside, only to see that no one is here, though there are comfortable furniture; a couch, a TV, a video game console with a pair of controllers, a coffee table and some decorations as well. Standing on top of the coffee table was a flask of sparkling magic potion.

Curious about the potion's sparkly appearance, the hedgehog decided to take a look at it to see what's going on. This is interesting, he thought, I wonder who created this thing. For a split second, he saw a tag attached to its neck. It said;
"My first attempt to create this potion is super annoying. It can barely make its own magic show up once I mixed one with another. I tried and tried, but I barely make it work. Can anyone like a blue blur in red shoes get to drink it in order to see what happens? - Heartina R."

How annoying, Sonic thought as he opened a flask, that kiddo may be a devil in disguise, but not too devilish. Then he decided to drink the potion, finding that it tasted like tropical fruit juice. After he finished chugging it, the hedgehog went out for a walk, only to feel a minor pain on his head; which was actually a splitting headache.
"Silly Heartina Rosebud must be one cheeky puppy," he groaned as he attempted to resist it, "gotta find a cure and fast."

Despite the pain, Sonic took off to run as fast as he could, only to bump onto trees and stuff until he arrived at the park. Because if this, a splitting headache worsened, forcing him to stop on his tracks. The blue hedgehog moaned and groaned in pain before he knew it.

"Ok, ok, ok," he complained, "this is gonna get super creep-EEEEEEYYYYYAAAAHHH!"

Sonic's head suddenly started shaking itself, then, in seconds, it started dividing itself like an amoeba separating into two separate cells, and that moment, it had split into a pair of identical Sonic heads, each with a mind/personality of its own; though the only thing they retained is Sonic's memory.
One of the heads was talkative and immature on the outside, but brave and cocky on the inside. The other head was slightly more clever than the first, but with a shy and innocent nature.

Sonic, now a two-headed hedgehog, didn't know what's going on.
"Oh wow! That is too insane for a hedgehog," said the first head.
"Agreed," said the other, with his ears folding his eyes "I-I-I think it is..."
The first head was astonished, perking up his ears. "Boy, this is weird. How come I'm hearing myself speak?"
"B-because us hedgehogs are good at hearing, soooo..."
The first one felt the second head with his right hand, scritching its fur. "I like your fur," he purred, "it's kinda feels like mine, I guess."
"Agreed... Yours, too."
"Well, do you think we share a same set of memories as each other?"
"Uhh..." The second head uttered, with his ears drooping. He rubbed his forehead with his left hand like a cat grooming its face with its front paw.
"Sooooo, you surely don't speak too many words, don't you."
The second head smiled and nodded. "True that..." he purred.

The first head of Sonic felt aware that the second head had a sweet demeanor. The blue hedgehog's two heads were curious about each other's personality, glancing towards one another's emerald-green eyes as he crossed his arms. His tail raised up, moving back and fourth like a dog's tail wagging.
The first head took a liking of the second head and scritched his fur behind his perky ears with his right arm. The blue blur was pleased.