You are Tails. Eggman had wanted to turn you to his side for a number of years now, and finally he had the opportunity to do it. Sonic had gotten frustrated with you, and called you some pretty bad stuff, so you had went to an isolated spot to cry.

While you were crying Eggman of all people came up to you with Metal Sonic at his side. Metal said something about guarding (You have managed to partially learn what his various beeps and tones mean), and then walked off.*

Eggman: "Greeting fox."