Façade
1. A superficial appearance or illusion of something
Toya knew from the very beginning that his friend wasn't human, and it only took him a little while to realize that his friend didn't know either. But every time Toya tried to tell him, he would get interrupted. He knew their was no such thing as coincidence, and he was sure that someone didn't want him to tell his friend that he was a false form, a body for someone else to inhabit. But, he knew he had to tell him at some point. He didn't like lying to his best friend, and to him, by not telling him the truth about himself, was the same as lying. He just didn't know if he wanted to ruin his best friends happiness.
Sorry it's short! I'll write a longer one next time.
DISCLAIMER: I do not own the story of Cardcaptor Sakura or any of its characters.