Excuse me while I get emotional for awhile! 😭 While all the craziness of the Starfall Islands is going on, Amy, Knuckles and Tails all have epiphany moments after seeing the Kocos' memories. They all want to go out on their own, see the world and follow their own dreams. And Sonic supports them 100%. It connects to the comics as well (obviously since Ian Flynn wrote both).
It's Sonic's philosophy to be free and move forward, and that's what the others are doing. Amy wants to spread love and help others, Knuckles finally decides to take the time to explore the world rather than just staying on Angel Island, and Tails wants to grow as his own hero. They're moving forward, and Sonic wants to them to see it through.
This is what makes him being corrupted so much more painful.
This isn't just about saving his friends anymore. It's so they can live their dreams. Having their freedom, even if it costs Sonic his own.😢