True, but the demons he's encountered have been mostly dangerous

Right. But most passive demons tend to keep away from demon slayers, for reasons that're easy to guess.

Yeah. As he looks at the tiny lizard, he's reminded of the light snake that hurt the poor kit that he took outside...

Well, basilisks aren't light demons. They're what's called 'grey' or 'null' demons, because they don't actually fit into any of the other categories.

He nudged his horse forward

One of the little reptiles has climbed onto the horse, and is clinging on to the horse's tail.

The horse snorts again and whips its tail

This just ends up flicking it onto the horses back.

The horse rears and then bucks, almost sending Elton to the ground

The little lizard-thing lets out a tiny, scared squeak and clings to the horse.