Alternatives to lichdom for a GOO daemon?

I play a big old warlock – his boss is a living demiplan of knowledge that manifests itself in the form of a dark and endless library with something that is always hidden in the privacy of one's eyes.

He serves his client by constantly collecting and sending out any magical, forbidden or simply new information that he can find. My DM did not really use the client as a guiding thread for the plot, but I thought about what would be the ultimate goal of my characters: the boss, and I think that's the only thing I've ever done. he would eventually like to be elevated to the rank of privileged servant of the latter, like a lich.

However, the lich does not feel Lovecraft enough, at least as it is commonly described. A mind setter might be more appropriate (given the telepathic characteristics of the GOOlock), but it still seems a bit false.

Are there any other Far Realm / extradimensional / Lovecraftesque equivalents that I do not think of?