Hollykit/paw/leaf is one of the five main characters of the series, and will grow from a child into a full adult over the course of that time, but she isn't in prominence for the whole series. That said, she has what might be the largest emotional range demands of anyone in the cast, as she goes from a strict, prickly, and bossy demeanor to unsure of herself to flat-out breaking emotionally and having a mental crisis. Her emotional journey through the series is the most clear and in-the-open, so the actor needs to be able to portray that.