Neville has a power of 9 which is enviable. Power 9's can't be disarmed by anyone other than a 9 or 10 and are more likely to be chosen as heads of houses. Neville is in charge of helping people swap from the dark side to the good side. So to become Neville:
1. You must be in Gryffindor
2. You can request to become him on this thread, just post a reply and ask.