After watching the first episode, Pantheon Legundo gives off kinda hidden melancholy/longing in a way? His loud and boisterous personality is on one hand just how he is, but he also seems to use it to hide his actual feelings in some situations. (The first time he seems to "drop the mask" is when they lay eyes on the mountain for the first time and Pyro remarks that the gods seem to have taken everything beautiful of the mortal realm and placed it there.)
Pan!Legundo might also harbour some less than expected/ideal feelings towards (at least some of) the gods. I wouldn’t call it animosity, that’s not what it felt like to me, more so that he seems to dislike the way they act or treat things related to the mortal world.
(Crack theory: Imagine he lost someone important to him because of a gods actions when he was alive but learned to kinda move on and keep going and now he keeps being reminded of what he lost because of the gods constant interference.)