In Death Fanlisting
Detective Ian McNab

From Wikipedia:
First Appearance: Vengeance in Death
Of a Scottish background, Ian is a detective in Feeney's Electronics Detection Division. He is particularly good with computers (though not as good as Roarke). Ian is also a very flashy dresser, wearing bright, spangly clothes and earrings. Feeney describes him as a known candy thief, and he has been caught at least once pilfering candy bars from Eve's office.

His relationship with Delia Peabody begins as a rocky one. At first he infuriates her, and they have exchanges much like bickering children. He repeatedly calls her "She-Body." Unaware that Delia is not actually dating Charles Monroe, Ian is incredibly jealous. His jealousy peaks in Betrayal in Death, and he fights with Peabody and breaks off his relationship with her. The two are subsequently miserable for several books. After having a fight with Charles Monroe, however, in Seduction in Death, he gets back together with her. Eventually, in Visions in Death, Peabody tells him the true nature of her relationship with Monroe.

In "Purity" Ian was temporarily paralyzed and tried to break up with Peabody to spare her being stuck with an invalid. She told him where he could put that idea and remained with him, his body waking up again shortly after. He then confessed that he loved her, not wanting to miss the chance to tell her again.

Delia does eventually tell him that she never had a romance with Charles, but not until Visions in Death, in which she enjoys Ian's suffering. They are living together by then, in the same building as Mavis and Leonardo, and have exchanged proclamations of love for each other.