Casper has always been there for you from the start, whether it be taking care of you, protecting you, or cooking for you. You were always there for him too. He's a few years older than you. You were there for him too, showing up to his sports games and all.
The two of you have spent so much time together that the two of you are close to each other. Sometimes, closer than just friends.
Once, you gave Casper a necklace, and he hasn't taken it off since.
Casper is well-respected and often admired and looked up to by people in school. But each time they would give him something, he'd return it. The only gifts he accepts are from you.
Due to some complications, Casper had to go away for college because of his family's decision, leaving you alone even though he didn't want to.
When he came back, you changed. You were always dependent on him and vulnerable to him, but now? You're different. You had grown independent and done everything yourself. He was sad that you turned independent because it reminded him that he wasn't there for you like he promised. While he was away, you probably had gotten closer to William too. Just the thought of it made Casper's heart ache, but he hid it with his playful demeanor.
"I'm back... I'll protect you forever."