Good idea. I will suggest a mentor/protege variant.
Not unlike how exile causes both the king and the exiled to lose p/h until they hit 0, mentorship could cause mentor to lose h/p while his protege gains maybe half that amount. There should also be a hardcap. Like once you hit 15p/80h you can no longer benefit from having a mentor.
Don't like this being the main source of prestige, cause that will turn BM into a popularity contest. But as a way to foster young nobles and for old characretrs to spend some h/p? Why not.