Like Eevee, Jolteon's role in the series is pretty minor, but significant enough to have an idea about what makes him tick. It is clear that just like Vaporeon, Jolteon seems to want Kirby's attention and his approval, but in Jolteon's case it seems that it's just the way he is with everybody. Jolteon never wants to be seen as "uncool", so he tends to succumb to peer pressure easily if it means that he can fit in with his peers (or in the presence of strangers, not be seen as an anonymous nobody). Make no mistake, Jolteon's use of electricity is quite flashy, and he can turn a Pokemon battle into a spectacle. On the other hand, he is a bit of a try hard and often tries too hard, and he just ends up looking lame anyway for seemingly not having any thoughts or opinions of his own. Jolteon will even get himself into things he has no right to be getting into, just to win the approval of others. Umbreon considers him to be a tool, and doesn't respect Jolteon much.
Jolteon is otherwise very loyal to Kirby, in some ways to win the coveted title of being Kirby's "favorite Eon", but also due to the opportunity they've had to really grow stronger together via the Johto adventure. Kirby can always depend on Jolteon to be available for any situation that arises. However, he tends to be a bit restless and bored, lately, as Kirby doesn't seem to call upon him as much as he used to. It would probably be better if Kirby did, though, as idle minds are the devil's workshop.