esto lei en gaf, si knuckles no sale por que se supone que ha muerto, que le den al juego:
Okay, it seems that before Sonic's birth, Iblis pretty much was using the flames of disaster to "purify" the world. However, he was stopped by the "Sol Angel", a being of increadible power. She stopped Iblis and sealed the flames inside herself. However, the power made her die, and her spirit manafested itself in the baby Elise ( meaning that she now carried the flames. From that day on, a town was named for the angel, and it was called "Soleanna". The people who founded the town were Elise's parents, and they were the "Royal Family" of Soleanna. Then, the royal family sealed Iblis in the body of Sonic.
This was from a News Source, It seems. Also, It seems that 3 characters are actualy dying in this game. One is widely rumored to be Knuckles.
---
Silver's future story is not made known in this script. He is currently known as a seperate being created from Sonic's soul when he died, seems to havea connection to Shadow, as well.
---
However, Iblis wont't seem to die, and then he reveals a shocking revalation; in order for Iblis to disapear forever, it's "true soul trigger", Sonic, has to die. Sonic is about to give himself up when Knuckles, his longtime rival, uses the power of the Chaos emeralds to exchange "soul code" with Sonic, and therefore making Knuckles the new Trigger, whom then kills himself to be rid of Iblis. This is supposed to be "very heartfelt" and sad, as this is the real end of Knuckles. Afterwards, Sonic falls to the ground, crying, and Shadow puts his hand on his shoulder, and he says that Sonic has to be strong, for Knuckles.