The Dark Tower Wiki

Ermot is the mutant pet snake of Rhea of the Cöos. He is not especially big, and is quite smooth and sleek with shimmering green scales. He is also venomous, with four sets of fangs; Rhea appears to use his venom as a mild intoxicant, as she became pleasantly dizzy after consuming a small amount.

He is likely one of Rhea's familiars, as he shares a close attachment with the witch beyond what a typical snake is capable of. He is well trained and closely guards the ironwood box that Rhea keeps her most treasured objects in. It is also heavily implied that he performs sexual services for Rhea, as the witch once remarked that "no man could do you like Ermot could do you" as the snake crawled up her pant leg.

When Rhea sent out Ermot to attack Roland Deschain and Cuthbert Allgood (under their aliases of Will and Arthur), Roland shot the snake dead.

Despite her enthrallment to Maerlyn's Grapefruit, Rhea was distraught over his death, and attempted in vain to resurrect him. Afterward, she sewed his severed head and mangled body back together, and draped him over her shoulders as a memento. She continued to wear Ermot's corpse long after it began to molder and rot.