Well, I don't think she is an average kid because the plan 'get a deadly wound to become a vampire' requires for you to feel a lot of pain, the very thing that gets us an evolutionary tool so we don't die that easily, fear. In a lot of cases, children get hurt because they don't know how to assess a situation, leading them to awful choices wich brings bruses and broken bones. When facing the same situation that in the past brought pain, a kid would be a little scared and able to think better about what to do next. Al, being a 9 year old, knows that already, she lived for 9 years and is very smart, as we were told. Even after executing that plan, with a deadly wound, she wasn't freaked out, she was in pain but she wasn't acting like a regular kid would, no scream, no tear. She was calm, she was so cold blood she said "Let me drink your blood, that way I'll be your little sister forever". Yes, kids are impatient, but for a kid to go such lengths just so she could get what she wants is not an ordinary thing.