Jon Lyon is a Nemean Lion who currently lives in the Liverpool Avalon. His best friend is Paul Finn, and his brother is Lorne Lyon. Jon has a bad temper which has often resulted in property damage and having his medallion revoked several times by the Avalon Elders. He has even injured his younger brother once in his anger. Jon is has also shown racist tendencies as he believes "it's [not] a good idea to be friends with with manticores " when Lorne mentions his friend Ike Sandford, who is half-manticore. However he it is mentioned that he does not have the same issues with other monsters.
According to the reader questions, the best day of Jon's life was when he was 18 and finally grew a moustache  .