[Update: Tekashi 69, on his third day of testimony, accused rapper Jim Jones of being a Nine Trey gang member.]

For the entirety of his brief, meteoric career, the rapper known as Tekashi 69 (or 6ix9ine) fashioned himself as a recalcitrant hellion, intent on instigating conflict for its own sake. He baited law enforcement on social media with guns and money. He live-streamed himself in bed with other rappers’ girlfriends.

But on Wednesday, in a federal courtroom in Manhattan, the 6ix9ine persona vanished. In its place was considerate, cordial Daniel Hernandez, the Dr. Jekyll to 6ix9ine’s Mr. Hyde. He was there for a purpose his alter ego probably never foresaw: to testify against his former crew, the Nine Trey Gangsta Bloods.

On trial are two of Mr. Hernandez’s former confidantes, including Anthony Ellison, an alleged high-ranking member of the Nine Trey gang who once served as Mr. Hernandez’s bodyguard.