The book was simple. Cassarah spoke so many times of it in the original timeline, Leneas could hardly forget it even if he [i]tried[/i] to.

"The River of Steel by Finnian the Wanderer. As a bonus, I'll even help you with the demon numerical system." Leneas did not want to mention it, but he found the human system harder to get used to that the demons'.

Leneas got to explaining Astech. Leaving out personal details, he described the giant, red-skinned demon as he knew him. A lot of it was guesswork, and could hardly be applied to the broader spectrum of demons Astech was related to, but hopefully, Cassarah would be satisfied by it.

2 hours later, he finished his explanation. With an inward sigh to draw some breath into his parched mouth, he felt the dry sting of air upon his even drier mouth. 

"Crap, I'm thirsty as hell. Do you want to get a drink, Cassarah?"