The chthonic snakes don't count as reptiles for Murphy's 'battle x reptiles' quest, unlike all the natural snake species, and the stellar snake-ish things. The latter implies it isn't the chthonic snakes' unearthly status that keeps them from counting. What could that possibly mean? He's protecting his own, obviously.

(And he must be obscenely powerful for a minion, seeing as he persists year-round, and existed in Lioden long before Apophis first arose... not to mention, there are days it seems he controls the RNG...)

That is all. Blame hunting quests on the Chaos Serpent.