This AU is gold ty <3~ Yuu, what happens when you do feed on lust? You grow stronger, yes, but what does it entail? Do you eventually 'consume' a human soul or their lust source? Or can you live with them? Do incubi age and die?
We incubi cannot die from age, but if our master happens to lose their humanity then we are susceptible to be killed by them. Such instances are extremely rare, though. I only know one incubus whose master became a demon. He had to devour her completely.