Working through Lenin's State and Revolution. Decided that it was time to actually bother reading theory rather than just going on what everyone else says.
As for nonfiction, rereading His Dark Materials. I read it once years ago, really hits different. The church-controlled word is scary... (I'm assuming one of the main divergence points there was the successful crushing of the Revolution.)
Been slowly working my way through le Carré's Karla Trilogy, but slowly starting to hate it more bit by bit. I still think spy stories are better if the setting is the Cold War.
I think now I prefer nonfiction and theory books more now, though, as I continue to learn. Should probably focus more on actually getting through them rather than reading snippets or shorter works as they come up, especially since sometimes I feel I'm not getting the full picture as I'm not entirely confident in my foundation of knowledge. Got a lot of stuff I'll probably have to reread at some point.