In "Insidious Intent," Val McDermid explores the troubling dynamics of a relationship strained by one partner's struggle with alcohol. The conflict manifests in sharp arguments and uncomfortable silences, highlighting the emotional turmoil both individuals face. This tension reveals the deep challenges of navigating such personal issues alongside the complexities of intimacy.

Tony, who embodies a profound empathy, experiences the weight of his partner's sobriety as if it were his own burden. His sensitivity to her pain showcases the intricate connection they share, demonstrating that her fight against alcohol profoundly affects him. This shared suffering illustrates the broader theme of how addiction can ripple through relationships, affecting everyone involved.