The more Ariel did the easier it became for Amadeus to not have to fight himself over wrestling control away. That was because he managed to get lost in the feel of each of those bites that made him feel like Ariel might actually succeed in his goal. From the sounds he made each time those fangs sunk into his flesh it certainly sounded like it. If they had not been Kindred this probably wouldn't have even had a chance of working. And even then it was still unique given Amadeus response to Ariel's bite alone.
"Lower." A plea. A request. One that his lover would have to unpin him in order to do. "I'll behave" he managed to rasp out.