If he's pulling the Hellfire out of her, then it could act as an energy transfer and give him a short term boost. But if it's more of a 'keep the fires low' thing, then he doesn't get anything out of it beyond having a means of attempting to hold it over her head as a perpetual favor owed/threat to use against her if he gets pissed off.
At least at the start. He does a lot of posturing and threatening that he pretty much never has reason to make good on - his dragon lieutenant he regularly threatens with skinning or ripping out his 'dragon bones' but it's all bark and no bite because Shangque is more valuable to him alive and whole and he recognizes that.
Considering her position in canon, she's probably the only one who could immediately peg him as a Lord of Hell (if a different universe's) and the tyrant nature that comes with being that after he gets his power back because he just feels Hell-aligned and suffused with Hellfire to those who might be sensitive to it.
no subject
At least at the start. He does a lot of posturing and threatening that he pretty much never has reason to make good on - his dragon lieutenant he regularly threatens with skinning or ripping out his 'dragon bones' but it's all bark and no bite because Shangque is more valuable to him alive and whole and he recognizes that.
Considering her position in canon, she's probably the only one who could immediately peg him as a Lord of Hell (if a different universe's) and the tyrant nature that comes with being that after he gets his power back because he just feels Hell-aligned and suffused with Hellfire to those who might be sensitive to it.