In her last performance of the night, Rihanna performed a medley that included "Stay" and "Diamonds" — a series of songs that showcased her vocals, as opposed to the party anthems and dance tunes that made her famous. The arrangement was pared down, by Rihanna standards, at least — there wasn't any flash, just Rihanna belting out those ballads accompanied by an orchestra.
And she sounded fantastic — as good as any performance of the night (including the fearsome force of nature known as Beyoncé). She hit the notes she was supposed to hit (unlike, say, the Chainsmokers, who earlier performed their hit "Closer," before Rihanna took the stage to obliterate the memory of them), but she also filled the songs with a lot of feeling and emotion.
After her songs, Drake presented Rihanna with a statue for the Video Vanguard award — recognition that she's one of the most influential artists in the game today. Not that we needed any more after her performance.