"Then you are significantly younger than I am, my dear. I've been on this mortal coil for over two centuries."

Undead coil was more like it, but he wouldn't out himself. Elves were thankfully long-lived so there was no need for him to lie about his age. Astarion did realize that he had been very young when he was turned, but by now he was most certainly considered an adult even by other elves.

"You've studied them that closely already, have you?"