The rapper born Jeffery Williams was not quite a household name in the fall of 2015, but to the discerning listener, he’d earned the title of hip-hop’s most fascinating stylist, not to mention its biggest enigma. For a year, the Atlanta native had flirted with mainstream recognition with cameos on singles from T.I. and Tyga and with 2014’s super-catchy “Lifestyle” with Rich Homie Quan. But as a character, Young Thug remained a mystery whose personal lore (like his confounding beef with his idol, Lil Wayne, or the revelation that he “wrote” his lyrics by drawing weird doodles) only added to the intrigue. The first installment of the Slime Season series, initially pegged as a full-length collaboration with producer London on da Track, was delayed by a massive leak of Thug songs in May 2015, including most of the original mixtape. Upon its release in September, the tape had been reimagined as a sprawling grab bag of moods and producers (among them Metro Boomin, Wheezy, and Southside) that lacked the clarity of its predecessor, Barter 6. Instead, it offered a buffet of Thug at his most gloriously freewheeling, from the monster hook of “Best Friend” that went viral on Vine (you had to be there) to non sequitur-filled mood pieces like “Draw Down.” Here and there, trap luminaries appeared for a quick verse—most puzzlingly, Lil Wayne on the tape’s opening track—but at the center was the unknowable, unparalleled Thug.