As for the team rocket thing he could just be there just in case something happened like the way you had said it. To the whole why she wouldn't know about him is much like Valorie he would have sneaked out a lot but one time he did it he never came home. Being as the Dad wouldn't be home a lot he wouldn't have really known him much other than being a no good brat. My char would have disobeyed, ignored and just have been a pain.
After being gone for many years he would be presumed dead with only memories of him being a disgrace. Though they might have seen him on the news or something they would ignore it and not tell Valorie about it because to them he is dead. This is all I got so far so let me know what you think.
Alright well I want to make a teacher char and I was wondering if his real purpose of being there would be investigate Team rocket activity and overall be the protector of the island. Also I was wondering if it would be ok or even possible to be a older sibling to your char valorie, someone see never knew only he did. Any of this sound good?