Wow, I didn't remember at all that Gamu is pretty stubborn (and very spoiled) in those early episodes. In fact, it seems to me that he has manipulated practically everyone (yes, even ULTRAMAN) to do his biddings.
(I suppose it's a contrast to Daigo (Ultraman Tiga), who seems happy to follow the rules most of the time (similar to Ultraman Mebius, imho). I can probably count on one hand when Daigo runs off alone (to do his own things). On the other hand, I lose count of how many times Gamu just does whatever he wants in the first four episodes alone. I guess I never noticed since I usually watched Gaia after Dyna, and they are probably less different than I originally thought. (The scary thing is I actually think Asuka (Ultraman Dyna) is more of a good kid than Gamu is in their respective early episodes).)
IIRC, only Atsuko and Kajio seem to be less than friendly to Gamu (but since he is the main character, they warm up to him eventually anyway). (For some reason, I think their reactions seem almost like the typical cold shoulder treatments someone gives to his/her potential love interest at first. Nah, I probably read too much into it. They both call him a kid and tell him not to use XIG as his playground or something.)
Hmm, could be just me, but Gamu reminds me of Yazumi (the computer whiz kid from Ultraman Tiga). However, unlike Yazumi, Gamu can actually get things done successfully. So I suppose that's the reason I overlook his (numerous) disobedience. If he could back up his claims with results, I don't mind him not following the rules.
Come to think of it, Gamu actually fits the character type (outgoing, nonconforming scientist) I really like, but why oh why I always thought he was so ordinary*? He certainly doesn't -- he thinks he is special! I actually don't remember many Ultraman hosts (main characters, I mean) who are that confident (bordering on looking down on other people) of their own abilities.
(*Perhaps I could blame it on where I first saw him. On that crossover movie with Tiga and Dyna (the one during his series' time, not the one from five years ago, although I think that one was also guilty of making Gamu pretty unremarkable). I don't remember anything interesting in particular save that, 'okay, this Yazumi clone is Ultraman, they don't usually use scientist type for that'.
Perhaps it's only me, but I always think an Ultraman host often changes his personality (or at least the writers change it for him) to become ordinary (i.e. a good kid, even if he is not like that in his own TV series) when he is in any type of crossover movie. Ultraman hosts only seem to keep their unique personalities in movies and tie-ins from their own series (no crossover with other series, even if they are set in the same universe).)
Not about Gamu anymore, but there are not so few familiar faces (to me) in Ultraman Gaia. So far there is Kougami's actor (from Kamen Rider OOO) as Chief Tsutsumi. And perhaps he isn't around in the first four episodes, but Captain Serizawa's actor is the third pilot of Team Falcon. And and and Hassei Takano (Kamen Rider Raia) as Fujimiya.