After the show, the pair posed for pictures with Amerie’s son. It’s been years since Amerie has performed on television, but she took to the stage on Ellen to sing along with 2 Chainz as he delivered his single “Rule the World.” The song features Ariana Grande, but the Rap or Go to the League track samples Amerie’s 2002 hit, “Why Don’t We Fall in Love.” Grande is out …