I’m bad at explaining things but for mine, I just get to the point and explain why I want the URL, for example, “I like this character they’re important to me” could be a reason to use (don't rely solely on this reason) but just genuinely explain why and what you would use it for, be honest about it. You could say you want to use it as an information page, art page, love mail, etc. I also sometimes add things like “I believe I would be the best choice to put this URL to usage” and things like that, you can also add because after and then list some more reasons. Very sorry if this isn’t helpful