DC’s mature-reader imprint DC Black Label has yet another success story on its hand with Harleen by Stjepan Šejić. The three-issue Harley Quinn origin story has hit the New York Times bestseller list in the Graphic Novel and Manga category.

Šejić’s dark tale offers a “haunting modernization” of Dr. Harleen Quinzel’s transformation from a promising psychologist to a psychotic supervillain. The mature tale also delves deep into Harleen’s dangerous relationship with the Joker. The comic finds Harleen eager to test a theory that mental illness is a survival mechanism. Drawn to the Joker, she soon descends into a cycle of madness and violence.

Unlike most comic book characters, Harley Quinn first appeared outside of the comic book medium, first showing up on Batman: The Animated Series. Created by series writer Paul Dini, the character first appeared as the Joker’s jester-like henchwoman and became a breakout character over the course of the seminal series. Harley’s origin as a former psychologist first appeared in the 1994 graphic novel The Batman Adventures: Mad Love. She first appeared as part of DC’s established continuity in the graphic novel Batman: Harley Quinn, during the No Man’s Land storyline. After DC’s  New 52 reboot, Harley’s origin also included the Joker kicking her into a vat of chemicals, given her bleached white skin the process.

One of the most controversial elements of Harley Quinn’s mythos is her often-toxic relationship with the Joker. This is shown as far back as Batman: The Animated Series, where the Joker is considerably less interested in Harley than he is in beating Batman. When Harley either messes up Joker’s plans or more likely, comes closer herself to doing in the Dark Knight, the Joker becomes increasingly violent with her. In both the current comic continuity and the recently-released movie Harley Quinn: Birds of Prey, Harley ends her relationship with the Joker, and in the comics, pursues a far more healthy relationship with fellow supervillain Poison Ivy. In addition, Šejić’s Harleen has been praised for its more nuanced handling of the title character with a more realistic depiction as opposed to Quinn’s more exaggerated appearances.

Ultimately, the success of Stjepan Šejić’s Harleen has gone a long way to proving DC Black Label popularity is no fluke. The imprint was initially met with plenty of skepticism following the closure of DC’s previous mature-readers imprint, the iconic Vertigo. However, the success of projects like DCeased, Batman: Last Knight on Earth and now Harleen have confirmed that, for the time being, DC Black Label isn’t going anywhere.

More: DC: 5 Reasons A Birds of Prey Sequel Won’t Happen (And 4 Harley Quinn Movies You Didn’t Know Were Coming)