It’s hard to say when, exactly, 50 Cent crossed the line in his feud with the Miami rapper Rick Ross. The more apt question might be: How many lines are there? He tracked down the mother of a Ross associate, DJ Khaled, at work, filming her sleeping on the job. He taped himself taking the mother of one of Mr. Ross’s children to buy a fur coat. He acquired and posted to the Internet a pornographic video starring another of Mr. Ross’s ex-girlfriends.

Rick Ross must have seemed an especially easy mark  it had already been a tough few months for his fourth wall. Before he was Rick Ross, the drug boss M.C., he had been William Leonard Roberts, and last summer a photograph surfaced of him from the mid-1990s, graduating from a corrections officer academy. He denied its authenticity  until The Smoking Gun got hold of his Florida Corrections Department personnel file, which included a certificate for perfect attendance.

The facts of Mr. Roberts’s life were getting in the way of Mr. Ross’s career.

To all this upheaval, Rick Ross  who, while he has been popular, has never quite been great  has replied, improbably, with art. “I see no reason to run to the dark,” he said in a recent interview in the Manhattan offices of his label, Def Jam. His songs aimed at 50 Cent have, hands down, been sharper and wittier than those of his rival. And the just-released “Deeper Than Rap” (Maybach Music/Slip N’ Slide/Def Jam), his third album, is unexpectedly fantastic, by far his best.