Babysitter Needed - Full-time / Part-time

I'm looking for a reliable, caring person to occasionally help with my 11-year-old son. I'm an elementary school special education teacher, and since he is in middle school, our schedules don't always align. I may need help on half days, school holidays, occasional pickups, school bus issues, or simply staying with him while I run errands. He is independent, so I'm not looking for someone to hover over him or treat him like a little kid. Ideally, I'd love someone with a big sister or big brother type of energy, or a warm, caring adult who understands his age. Most importantly, I'm looking for someone dependable, respectful, flexible, and easy for him to feel comfortable with.