I am looking for a book series that upon completion will leave a feeling of emptiness, as if I'm saying goodbye to a good old friend, when you realize the good old days were left behind. It's a shitty feeling that only comes after something great, something that left a mark on you.
Oh, absolutely agree with everything you said. Tbh era 1 of mistborn also fits what op is asking for in the "saying goodbye to a dear friend" feeling.
I'm a big Cosmere nerd, so I've been through the whole thing multiple times now.
Love Secret History as well.
Also heh, Invested. Me too, I have been for years.
Can't wait to see what Apple does with it!