'Shadow and Bone' made Tumblr's dreams come true. Now it's reaping the fandom rewards.

There's being a fan of something and there's being in its fandom. Being in the fandom of any particular property means a person identifies with their love for that thing and seeks out a community of others who love what they love. Fandom is engaging with fanfiction, coming up with headcanons, and fancasting characters for...