As the series progresses, Delaware's relationship with Robin Castagna evolves, despite two long separations, during which various other romantic interests are introduced.
In some of the more recent books in the series, Detective Petra Connor, introduced in Kellerman's standalone novel Billy Straight, also makes an appearance.
Kellerman also adds a girlfriend, Robin Castagna, and a French bulldog, which serve to emphasize Delaware's empathetic nature.
[3] Kellerman's characterization of Delaware is typical of the "Post-Modern Detective" whom Professor Dick Gibson defines as "often an untrained amateur ... often sensitive, caring, thoughtful and socially aware, and he is often from a traditionally noninvolved group.
"[3] Kellerman characterizes Delaware as "sensitive, socially involved, loving and passionate about his patients and his family relationships and cynical only about 'bad guys.'"
"[4] Some reviewers, however, have criticized the Delaware novels based on overly intricate plotting, too much description of unnecessary elements, and "formula characters.
In Blood Test, Alex Delaware acts as a consultant in the divorce and child custody case of Richard Moody, a bipolar and potentially dangerous father of two.
[9] In Over the Edge, Kellerman presents Delaware's back story as a researcher in the study "Project 160", that involved the treatment of gifted children.
During the course of the investigation Delaware encounters dysfunctional families and political extremism as he races to unravel the real villain as he pulls together all the threads.
[15] Thirteen months after the events in Bad Love, Delaware meets a former patient who sat on the jury in a serial killer case.
Unraveling the two strands, Kellerman has Delaware face repressed memories, murder groupies, jailhouse autobiographers, all on the trail of a serial killer.
A complicated plot, laced with ever-present murder, and a weird experiment gone terribly wrong is woven through the uneven writing, uncharacteristic for Kellerman.
[17] In The Clinic Kellerman presents Delaware with a cold case of murder, and the victim was a "pop psychology" author named Hope Devane.
[24] In Therapy, Delaware and Sturgis investigate the death of a double murder on Mulholland Drive that leads to human rights' atrocities in Rwanda.
Teaming up with Milo Sturgis, Delaware encounter "wayward children, a foster family from hell....and a serial killer who's the exact opposite of the genre's usual madman slasher but just as deadly."
When one of the actors is murdered, Delaware and Sturgis follow the clues that show the two were prey to an odd acting coach and an aspiring real estate developer.
[28] In Deception, Deputy Chief Weinberg assigns LAPD Lt. Milo Sturgis the particularly sensitive murder case of Elise Freeman, a teacher and tutor at exclusive Windsor Preparatory Academy in Brentwood.
As the investigation reveals a victim that had a lot to hide and a boyfriend, students, teachers, administrators as well as a Deputy Chief who are all anxious to keep those secrets hidden—and at least one of them is willing to kill again.
In Mystery, Delaware and Sturgis tackle the online dating world, when one of its sexy girls gets her face blown off in real time.
Said website sets up sugar daddies with young women ("sweeties") looking for someone to take care of them, but all hell breaks loose when corpses variously mutilated start turning up and a rich family is somehow involved.
A serial killer à la Jack the Ripper, with disemboweled victims lined up in ritual precision, where compulsion and obsession mix in an explosive cocktail of violence and gore.
In Killer, Dr. Delaware becomes briefly embroiled in a bizarre custody battle between two sisters; one, a sophisticated, successful doctor, the other, an itinerant groupie.
When the former is found murdered and the other disappears with her child, gay LAPD homicide detective Milo Sturgis will need Dr. Delaware's insight, expertise - and instinct - to solve the case.
The investigation uncovers that, aside from the Corvins, the rest of the community is particularly secretive and uncooperative, and unwilling to divulge information to Alex and the LAPD to solve this violent crime.