E. L. James’ Fifty Shades of Grey was the best-selling book of the 2010s, so you’d be hard-pressed to find a book that’s been more successful in the years since the trilogy first appeared in stores. With that being said, we think that the series most comparable to Fifty Shades is Ruby Dixon’s Ice Planet Barbarians, a spicy alien romance series that took over TikTok’s reading community in 2021.