Now this list? Endless. I have so many books I want sequels or companions for, but I’m only picking a few here that I really want more of, because if I listed them all I’d have to take a year break (and you’d probably still be reading the list by the time I get back).
But, as this is relatively self-explanitory, I think we can just jump right into it easily.

Eleanor & Park by Rainbow Rowell
Now, this might not have been my favorite of Rowell’s books to date, but after reading the ending of it I would not be opposed to a sequel if only to know how the whole story went along from where it did. (Did you see that epic spoiler-dodging I just did there?)

Carry On by Rainbow Rowell
Now to follow with my favorite Rowell book: I WANT MORE OF SIMON AND BAZ AND PENELOPE OKAY. GIVE ME. I WANT I WANT I WANT.

The Night Circus by Erin Morgenstern
Now this one I could go for either a companion novel or a sequel from the POV of … a character from the book. Won’t say who, but if you’ve read it I’m sure you know exactly who I’m talking about. 😉

The Book Thief by Markus Zusak
Now this I most definitely want some sort of a companion novel or just something more from Zusak on WWII. Please. I don’t care what it’s about from the war, just please.

Teeth by Hannah Moskowitz
And I’ve said this a dozen times before, I’m sure, but I need a sequel. So badly. So badly, you don’t even know. I wrote freaking fanfiction for this one, okay, because I needed a sequel so badly.
Ugh!
Teeth. TEETH.
And those are the books I’d like sequels or companions for! There are so many more though. Enough to do a 2.0 of this post once I feel the need to.
Have any books you think need more? Please tell me! I love to suffer. I also accidentally hit capslock when I wrote that bit so that was almost more intense than it needed to be.
Thanks for reading!