Jimmy is a very arrogant, violent and egotistic teenage. He seems to enjoy doing the same things his dad enjoys doing.
Jimmy and Mega Kid seem to be best friends from the beginning of the series.
Jimmy seems to love Epona. In the episode Zelda's Fourth Triforce he has a heart above his head and stares at her the moment he sees her.
There is no apparent relationship seen outside of friendship between Maria and Jimmy.