Being Tremere, Amadeus never once thought twice about the fact that they used blood. He used blood for so many other things in his unlife that it just seemed natural for him to use blood for something like this as well. It worked and was much more convenient and that's all that mattered.
Given Ariel's mood he had not been expecting easy or slow. The claws sinking into his thighs was not expected though and caused the Elder to hiss between his teeth in surprise and pain. But then the pain mixed in with the pleasure. And those growls? Just made it all the better. "Fuck, Ariel," Amadeus gasped out as his lover took him.