Who thinks that The Twins are unfit to be parents?

The belief that The Twins are unfit to be parents is held by Enzo, the dog and narrator of the story. Enzo's perspective is shaped by his keen observations and deep understanding of human emotions and relationships. Throughout the novel, he reflects on the dynamics of the human characters, particularly how their behaviors and decisions impact one another. Enzo's thoughts and instincts lead him to form judgments about the suitability of The Twins in fulfilling the responsibilities of parenthood, interpreting their actions and the environment they create for children.

The other characters in the story may have varied opinions and feelings towards The Twins, but it is Enzo's unique vantage point as a dog that allows him to articulate a view focused on the wellbeing and emotional health of the children involved. His character serves to provide a deeper commentary on the qualities that make for good parenting, demonstrating love, stability, and a nurturing atmosphere, which he perceives to be lacking in The Twins' behavior.