There is a series with a sentient entity, living in a star. I think by Pohl. Anyhow, he passed before writing the next book, and it literally bugs me at least

There is a series with a sentient entity, living in a star. I think by Pohl. Anyhow, he passed before writing the next book, and it literally bugs me at least once or twice a year, and yet I read it 20? 25? years ago. So yes, at least here endings matter.