There isn't a specific fandom name for The Fault in Our Stars book, but John Green (the author coffee coffeelover #delhi #streetfood #food #foodie #foodlover #telugu #travel #shorts #happy #1m #friend #friendsforever #friendship #dog #travel #food #foodie #india ##love #delhi #care #short of the well aclaimed novel) has a small following of people called Nerdfighters.
He explains about this on tumblr and in his vlogs