*Zavok is not happy. Sonic humiliated him in battle. Eggman used him for his own benefit. The people that helped him were useless.

So he's back, for revenge, on both of them, and add the world to places to rule. Since you're either on Sonic or Eggman's side he's basically against your whole planet. You'd have to claim that you were quite the anti-hero for him to even listen to you.

So when he arrives in your town to attack, you don't expect him to try and make a deal with you. You have a single Chaos Emerald after all.. You had found it digging up soil in your backyard. The emerald happened to land there somehow. Lucky you, or maybe unlucky you, depending how you looked at it. You decided to keep it at the time.

"If you give me the Chaos Emerald, I may spare you, although you don't truly have a choice."