Because it's not written down tells me you have absolutely no idea how to articulate your personality in words, which presents a problem when making character interactions. Ever tried to wing a long speech? Given that's much more difficult, you'll be wrought with inconsistencies, not to mention it makes it difficult for other players to interact with you. Basically, you should be able to at least give a few sentences on how you want your character to act. If your character's personality is in your mind, and that just because it's not written down doesn't mean it's not actually there, then what's stopping you from actually you know... Writing it down if it's there?

Backstory is important in this RP too, remember, the premise is that we are "disgraced hunters". How did we fall from grace to begin with? That's why it's even more important in this RP than others, because of the premise of the RP requiring specific types of backstory.