[oof, this is about to become a bummer, isn't it. Sensing that this isn't the time for jokey joke bullshit, Sonic straightens up a bit and takes a more serious tone.]

No. As far as any of us know, including him, Knuckles is the last of the echidna. He was takin' a big risk leaving the island unattended, but we never woulda won the war if he'd just stayed on the sidelines.