Five top SFF novels featuring interesting, powerful friendships

Karina Sumner-Smith is the author of the Towers Trilogy.

At Tor.com she tagged her five favorite science fiction and fantasy novels that feature interesting, powerful friendships, including:
Archivist Wasp by Nicole Kornher-Stace

This post-apocalyptic ghost story grabbed me from the first page. The titular character agrees to travel to the underworld to help the ghost of a super-soldier find