Made a Demon of Myself

In this story it is about a 14 year old boy named Saige who wears a fake identity and no one knows his true self. His family sees him as a young innocent adolescent with a bright future ahead of him. But he actually has a demon fallowing him and helping him get by unnoticed. He has the instincts of a great killer or assassin. But is the real him still alive and just under control of the demon within him and around him? Saige has a twin who is in the light and want to heal the world from it's darkness. His twin's name is October and is fallowed by an angel, and yet the twins don't know either true identity and love each other equally. Would these brothers clash or is there a way to prevent it. Will the demon within Saige and the angel within October cause the brothers to clash and kill each other. Also will anyone find Saige's true identity.