In 2009, Harrison began touring the world with Doro as her keyboardist, appearing at festivals like Wacken, Graspop, and Sweden Rock, in addition to countless headlining shows everywhere from Los Angeles to Moscow. In May of 2013, he sang the official anthem of the inaugural Full Metal Cruise alongside Doro in front of an estimated 200,000 people at Hamburg Germany’s 824th Harbor Celebration. In 2015, Harrison joined the metal band, U.D.O. as their keyboardist. Harrison continues to collaborate both in the studio and on stage with Doro and Udo to this day.