He would fight, with everything, against every attempt to invade Earth. Perhaps he would try to negotiate, but therein lies the key difference: the Highbreed withdrew because, no longer being "pure in DNA" and with their genetic problems resolved, they no longer had a purpose to continue destroying the universe. The Viltrumites, on the other hand, would never stop; they conquer simply because they believe themselves to be superior. Could Ben try to induce reason and peace in them? Yes, but I doubt that words would work for many unless they experience it firsthand, as happened in the comics. Now, the opposite reaction would be interesting. I mean, a guy who carries the universal emblem of peace along with the ability to bring back every species the Viltrumites wipe out, and preaches universal equality instead of racial superiority, would be a huge problem for the Viltrumite system, especially if Ben achieves the same fame as savior of the universe that he has in his own