The old rap star metrics of greatness? Future has no use for them. In his songs, he employs few true narratives, no real wordplay or punch lines. He raps mainly in free associative snippets, which, taken as pure text, can read as mundane.

But what Future excels at — what makes him an undeniable star — is his gift for emphasis, and his ability and willingness to rewrite his vocal approach. He doesn’t toy with character like Nicki Minaj, modern hip-hop’s peak changeling, does. Rather, he fiddles with structure on a phrase-by-phrase basis. He’s interested in mode over content, or rather, mode as a means of content.

More than anyone, he has used the frictions of modern hip-hop to his advantage — he is a rapper and a singer, a technologically aided aesthete and a raw emotional purger, a street-centric braggart and a hopeless romantic. He’s idiosyncratic and identifiable enough that he’s become the go-to man for bold collaborations — he’s softened the edges of Rocko’s menacing “U.O.E.N.O.” and Lil Wayne’s “Love Me” but also collaborated on heart-melting love songs with Rihanna, with his fiancée, Ciara, and even with Miley Cyrus.

In so doing he’s become the genre’s first fully post-Drake, post-“808s & Heartbreak” star. His voice is one of the threads that unifies the hip-hop mainstream, and his second major-label album “Honest” (A1/Feebandz/Epic) demonstrates — as did the excellent “Pluto” before it — how what might in an earlier era have been solely an accent piece can now be the centerpiece.