As the original creator of the Creatures of Grimm, it can be assumed that the God of Darkness took extreme pride in his first creations. He would regularly send them out to destroy his brother's creations until the two finally made a truce.
After Humanity was created, the God of Darkness would eventually choose to settle down in the Land of Darkness and live among the Grimm. When Salem came to ask him to resurrect Ozma for her, a group of Beowolves can be seen peacefully living in the God of Darkness' main chamber, showing that he does care for them greatly and treats them like pets.
Later, after wiping out all of Humanity on the planet aside from Salem, he notably left his own creations alive.
The God of Darkness, along with his brother, the God of Light, used to love and value Humanity until Salem manipulated them and turned Humanity against the Gods. He was disappointed that the Humans used his gift of magic against him and his brother. The God of Darkness ultimately decided to destroy Humanity for betraying him.
As implied by his argument with his brother and him having initially granted Salem's request, it is shown that the God of Darkness is jealous of Humanity's positive view of his brother and would also like to have the same genuine faith they give him.
The God of Darkness is the younger brother of the God of Light. He appears to be hostile towards him and his ideas about life, but does show loyalty and caring towards his older sibling. When his brother told him the truth about Salem, he put his pride aside and apologized for his actions by destroying the resurrected Ozma. He also came to his side when Salem's rebellion invaded the Domain of Light.
At first, the God of Darkness was impressed but very pleased, that she chose him instead of his brother unlike the rest of Humanity, and granted her wish to revive her deceased lover. After his brother told him the truth about Salem, he was angered that she asked his brother first instead of him. The God of Darkness along with his brother cursed Salem for her selfish and demanding nature in her attempts to revive Ozma.