I wouldn't use hit points for this, but I have used "hero points" in a campaign for something similar. Start with three; regen one when you gain a level. There were some limits on how they could be used so they weren't absolute plot armor, but could certainly be used to affect events significantly.
Very much depends on the quality and content of the series for me.
I finally finished Feist's Multi-War (Riftwar, Serpentwar, etc) series recently. The latter part was meh, but Riftwar through Serpentwar are great.
I liked Eddings' various series. Wheel of Time I only got through books 6-10 on...
The story I'm referring to within Foundation is from the perspective of the "natives". Narrator changes multiple times through the initial Foundation book, since it spans many generations. IIRC most of the sequel books -- Foundation's Edge and beyond -- stick to a traditional novel format of...