You're sonic's brother. This takes place at Green Hill, and the rest of sonic's friends are humanized as well.

You were resting on a huge pile of robots, Doctor Eggman sent like a hundred robots to capture and contain, but you're a better fighter than your brother, even though he was a bit faster. 

???: Hey (Y/n)!

"Hm?"

You looked down, and saw Tails with Knuckles.

"Oh hey guys, what's up?"

Tails: Not much, but we're glad you're ok."

Knuckles: Its been a while, huh (Y/n)?

"Yea, it has, heard that Egg head hasn't given up."

Tails: No, he hasn't.

Knuckles: Anyways, we need your help, Sonic, Shadow, and Sliver were outnumbered and got captured. 

"Sure, I don't mind breaking few more robots."

Tails: Awesome, let's get going!

"Ok"

You grabbed Knuckles and Tails, and just ran full speed, for Doctor's Eggman's lab. Without even triggering the traps, or the alarms. When there was huge metal door blocking the room in where Sonic, Shadow, and Sliver were at, you let go of Tails and Knuckles, and just kicked the door down. Mecha Sonic was there.

Mecha Sonic: Who are you?

"I'm (Y/n), and you got bros locked up in those cages."

Mecha Sonic: I'll end you quickly!

The robot ran at you, trying to punch you in the face, but you ducked and did back-flip while kicking Mecha-Sonic straight at other wall.

Mecha Sonic: Systems failing! Reboot necessary!

You ran to Sonic's cage.

"Hey Sonic, wake up man!"

Sonic: Huh? (Y/n)?! How'd you get here?

"Tails and Knuckles, anyway, i'm surprised you lost to a few robots."

Sonic: There was a lot of them, just please get me out this cage, i'm not as strong as you.

"Sure"

You grabbed two of the bars, and bent them out of their place.

"There."

Sonic went though the opening, and stretched a bit.

Sonic: Thanks, now we got get Shadow and Sliver out. 

"On it."

The alarm went off, a few robots ran in and ran at Sonic.

Sonic: Dang, i'll hold them off!

"Ok."

While Sonic was running around the robots, distracting them, you were breaking the bars are Sliver and Shadow's cages. When they were free, Shadow grabbed Sliver.

Shadow: Thanks for the help, we'll get Tails and Knuckles out of here with us. You and Sonic should destroy this place, Doctor Eggman might do something stupid.

"gotcha."

With Sonic, you attacked each robot and destroyed it a split second. When the all robots were down, you two ran for where the power source was at, and you found it. The power source was huge ball of electricity. You looked at your brother.

"Hey Sonic, wanna do it like last time?"

Sonic: Heh sure.

You and Sonic then jumped and ground pounded every wall, while performing tricks to get to another. The whole place was falling apart, when there was a huge explosion, Tails, Shadow, Sliver, Knuckles, and with Amy Rose saw it, they were on the beach.

Tails: W-woah

Amy: SONIC!!!!

That's when Sonic was flying in super form, while you were running on the ocean. Both of you had to that proud grins. 

Sonic: That was awesome!

"Yea, i forgot how cool it was to kick ass....Hm?"

You saw something blue running on the ocean. You then remembered about Mecha Sonic. You jumped up, grabbed Sonic, and threw him at the beach, that's when Mecha Sonic tackled you, the robot tried to go after Sonic, but you held onto it, really tightly, and threw him at the ocean. Sonic landed perfectly on the sand, while you still running on the ocean.

Sonic: (Y/n)!

"Mecha Sonic is still up."

Mecha sonic then rose out of the sea, and chased after you. You didn't stop, you almost ran into a wall, instead of going another direction, you ran it, and ran on the wall. In Amy's vision, she saw you ran on the wall, and Mecha Sonic crash into the wall, she thought you looked awesome doing that. You then ran to the beach and stopped, taking deep breaths.

"Wow, that was not easy."

Sonic: (Y/n), that was incredible! How did you learn how to do that?!

"I always trained, remember?" 

Shadow: That was impressive.

Sliver: Wait, Sonic, you can't do that? I thought you two were brothers.

Sonic: We are, he's the fighter, and i'm the runner.

Tails: Oh i get it, because you run faster, (Y/n) wanted to fight better?

"uhh yea, i guess you could say that."

Amy blushed and pressed her fingers together.

Amy: H-hey tt-that was really cool. 

"Hm? Oh hey Amy, it's been a while."

Amy then blushed harder, and was shocked.

Amy: (H-he remembers me?!!)

"Well, I if Eggman ever comes back, I'm here for you guys.

Tails: Wait, you're staying this time?

"Yep, I kinda miss hanging out with you guys."

Amy:(H-he's h-here to s-stay, d-do i h-have a ch-chance with h-him?!)

Sliver: Hm?

When you, Sonic, Shadow, Tails, and Knuckles were walking to back Green Hill, Sliver stayed with Amy.

Sliver: We'll catch up with you guys later......Ok so, you have a crush on (Y/n) instead of Sonic now, am i right?

Amy:.....Y-yes.

Sliver:....Hmm. Well why not ask (Y/n) out, he's a bit more relax and cooler than his brother.

Amy: But i don't know if i have a chance with a cool guy like him. 

Sliver: He might give you a chance.

Amy: You think so?

Sliver: Yea, now let's get going.

Amy: Ok

-Later-
You're currently on a tree, just taking a nap, when-

Amy: Hey (Y/n).

"Hm?"

Amy: I w-want to tell you something.

"Sure."

You got off the tree, and landed right in front of Amy. She was blushing really deeply.

Amy: Ok so uhhh.

"......Yeah?"

Amy: Well you see....i uhh....

"Let me guess, you left my brother for me."

Amy: What?! How did you know?

"Who else would blushes really red, and mutter when they're in front of me?"

Amy:.....y-yes, it's true, I love you.

You placed you hand on her head, and began to pet her.

"I love you too Amy."

You then hugged her. But-

"Wait, Amy, didn't kill other for Sonic?"

Amy: Yep, and I'm going to make sure you never leave my sight.

".....yay. (I'm screwed)"

Your pink haired girlfriend would now never leave your personal space unless you needed to use the restrooms.

-Author's Note-
Amy rose is actually my favorite character from Sonic X.