It was like flipping a switch, moving Alex from desire to all out Lust, prime material for her to feed on. The energy coursed through her like an electrical current, driving her mad as she took him deeper, sucking him all the way down.
As high as the power trip was taking her, she knew if she moved to fuck him then, she could easily kill him from the exchange- his body was still primarily mortal, no matter hoe much Sin he'd acquired. She needed to drain him some, first- while the experience would be less satisfying for her, it would at least allow him to live to feed her again, a trade-off she was willing to make.