Carlos was intrigued by Douglas from the moment he saw him for the first time.
Back then, he found himself unable to read the latter but his senses made him know that Douglas wasn't a simple man.
At first, he considered letting him spend some time in a waiting cell before finally releasing him but he escaped and what's more, in a way that was still unknown to Carlos.
Just now, his brethren had informed him about Douglas's unique use of ice and he had seen it with his own eyes the low proficiency with which he utilized it.
As a notable figure in Aragon, Carlos prided himself on learning much about the supernatural world which was why he was well aware that the Frost Domain was exclusive to werewolves and according to what was known, the werewolves were extinct due to an unfortunate accident several years ago.
So there were two things; it was either Douglas was a human Mystic that devoured a werewolf body part or he was a werewolf himself.