Besides having acquired knowledge of the Ashen Mask outside, the other reason why Grimm had returned to Black Isotta this time was to settle issues of profit regarding the perfume with Fatty[1].
The issue with the perfume profits was the Orchid Tree Commerce Union that Fatty served. It was a large power found throughout the Seven Rings Holy Tower's 11th to 15th Sections Dark Sorcerer faction and had wide influence over the Seven Rings Holy Tower.
When Fatty caught sight of the halo above Grimm's head, his eyes widened and he muttered, "Looks like the contract will be continued for several thousand years. The scheme[2] of that group of old guys fell through."
…
The fourth floor of Black Isotta.
A group of white goat-bearded sorcerers of short stature put down the books in their hands, pointing their fingers at the halo above Grimm's head in a daze. Not daring to believe what he was seeing, one of the sorcerers mumbled, "You qualified as a reserve Demon-Hunter?"