Seraphs are Site Directors, the bosses who run the site.
Angels and cherubs handle the mundane things to give the seraphs the time to do the tricky stuff. We red and green fellows answer the questions we can, swing the little ruler upon naughty fingers, and generally help keep the place running.
Seraphs can do all of that, and more. They plan, decide, create, and generally teach us others how to be better at what we do. They teach us a bit about coding, directing and other things so that we can help them do what they do, and maybe one day, run a site of our own.
All opf this in the the FAQ at RTWH. Give it a read- you'll learn a lot.