I can see the comparison between Guido and Wild Arms. They both seem to share a similar nervousness, though Wild Arms' seems to be more focused on the perils he's in or about to get into.
Wild Arms doesn't seem as eager to offer help if said peril is involved. I can't help but suspect Grandpa Longneck and Mr. Threehorn persuaded Wild Arms to help in the rescue mission with the reasoning that he owed Bron for having looked after him and he had a obligation to repay that debt. That must have pinged his conscience, since he agreed, albeit very reluctantly, to help.
Can't help but suspect Wild Arms will continue to feel he owes Bron for his kindness to the point that he will feel independently moved to save someone Bron cares about. He'd be the type who'd be dragged kicking and moaning into adventures while, in spite of himself, coming to like these adventuring people.