Everything corrupts and influences things around them. From the simple act of breathing in a room to the act of consuming food.
Even the simple act of wearing something will leave traces of oneself on those clothes, traces so negligible that one barely notices them. And yes, those traces are a kind of corruption as well.
Some people get paid hefty amounts to find such traces and people are paid to deal with these traces.
Like an Ant, that leaves its traces by moving pieces of earth around. A bigger and stronger being would have greater traces left in its wake. And no matter how much one tries, it's impossible to get rid of it.
That was the case with the flames that Adam had obtained from Maisel. Even the purest form of those flames that Varkus could conjure, would only be relatively purer than the real thing. Due to the very fact that the flames were connected to his soul. His mana as well as will would hold influence over those flames.
