Making a pact with a demon, demons strictly abide by the contents of the contract; if humans violate the pact, demons are not angry, but rather pleased.
Violating the contract shows that humans are greedy and untrustworthy; such human souls are... more entertaining for demons to toy with.
If demons see value in cultivating the soul of the person they made a pact with, they might secretly stimulate that person's desires until their soul becomes incredibly tantalizing, and only then will the demon descend to feast upon their soul...
As a banquet for themselves.
There are many types of demons, with various demons to be found.
The demon Andre made a contract with... is like the Blood Moon demon...
Blood Moon demons are entirely crimson, with claws like the blood-red crescent of the half-moon, and they revel in consuming fresh blood and souls.
During the Blood Moon night, Blood Moon demons absorb the aura of the blood moon, and ferocious bone spurs grow on their bodies.