I read a story years ago about an ordinary guy who gets kidnapped by aliens as they pass the sol system. While on their ship the aliens, who are feline, change the guy's dna to turn him into one of them but instead, he gets the dna of the alien's king, thus becoming the king. Lots of other things happen, fights with gods, planets, etc... It is one of the best stories i've read and i'd really love to find it again if possible. Any help would be great. Thanks.