The story
From slan (“fan of science fiction”) + -hood (suffix denoting a condition or state of being). Slan is from the title of the science fiction novel Slan (1940) by Canadian-born author A. E. van Vogt (1912–2000), about persecuted – yet physically, mentally and morally superior – telepathic mutant humans.
Etymology from Wiktionary, CC BY-SA 4.0.