Hello! Cruel Owen Quarrel here. I think that many companion idle animations are very interesting, but I don't know if all of them have any. As an example: Kobe YoJimbo has the model of a Ronin in MooShu, and as such he shares the same animation- cracks his neck both ways then hunches over, flexing. But I don't think any of the other starters have idle animations other than a single pose. Like Egg, my favorite companion. When walking he keeps one hand on his spear while keeping it behind his back, and one hand on his sword. When standing still he's just crouched with his hand swaying a little, but after a while he still doesn't do anything out of the ordinary. I'm not sure where Subodai falls into his category because while he doesn't do anything on the scale of Kobe, he does look around and his ears twitch, which is actually pretty adorable (don't tell him I said that or he'll kick me in the shins). This may seem not all that interesting but I think the idle animations are really cool. Unfortunately I've only caught a few of them. These are the ones I know so far (besides Kobe):
Hawkules- Flexes his muscles a bit and backs up, admiring his pecs.
Bonnie- Raises her musket into the air and checks it.
Lucky Jack/Any Jack Russel dog NPC- Raises his sword up against his shoulder and almost makes a shrugging motion, spreading his palm like "What can ya do?"
Gaspard- Kind of just looks around
Mormo/Any Water Mole Witchdoctor NPC- Looks around as well but it looks like he's saying something
Shiruku Neko- Scratches her ear with her blade

If you guys know of any more, please leave them here. Thanks for reading this largely un-interesting post!

Cpt. Cruel Owen Quarrel, Level 65 Mouser