I feel like Hastur and Pazuzu used to have many-a flings back when they had first joined the beast tamers, through a mutual feeling of sexual attraction and circumstance (with them usually being alone in the lab at nights), leading to a bond of trust to forge in-between their moments of intimacy. Over time they have shared their deepest secrets about their past life to one another, and one too many, at that
Hastur would once share that his past life involved the torture of human beings, but since Pazuzu is interested in all things gory, his support was met with looks of disgust from Hastur who had just confessed what he considered a grave sin
It is this reason that Hastur often now finds a bit of discomfort in the man he didn't proclaim his lover, but someone he had trusted and was attracted to. This disparity caused him to claim less and less of a relation between him and Pazuzu, much to the confusion of Pazuzu, who was still considering him to be a trusted person in his eyes
