Raymond the anti-hero...
In actuality, Raymond was the anti-hero of the film. How? An anti-hero is a protagonist who lacks the qualities that make a hero, ie, courage, altruism, idealism, moral strength. Raymond is lacking in these qualities; it is only after his cousin is killed and Peck makes a play for Kathleen that Raymond goes after Dennis.
It becomes obvious as the film goes on that Raymond has an ulterior agenda and it's not about stopping a criminal from victimizing the city or corrupting the LAPD, but about his own ego and his own "turf" and image.
Raymond becomes enraged at Dennis not because he is killing innocent ppl. and scamming others in real estate schemes, but because Dennis deigned to step on his "turf" and shatter the image Raymond has of his "perfect" family.
He also becomes enraged and hits his own wife because she made him look foolish by fooling around with his worst enemy. He's unmindful of the other customers in the restaurant where he confronts his wife; all he cares about at this point is dumping out his rage and humiliating Kathleen in the same way he feels "humiliated."
As the film goes on, it becomes clear that Raymond has stopped caring about doing the right thing, but about getting revenge. He becomes obsessed with retaliating against Raymond at the expense of his other responsibilites at work and at the expense of his fledgling working relationship with Amy Wallace (the true hero of this film) and his employee relationship with Chief Grieb.
Amy's injury at Peck's hands becomes Raymond's excuse for revenge, fueled by finding Dennis in bed with Kathleen.
He "gets" Dennis, is enemy, but at the expense of his soul and dignity. As the film closes and even when Raymond is holding Kathleen again, it's clear to see how far down Raymond has sunk; he has sunk nearly to Peck's level.
If there is a hero in this film, let's look no further than Amy Wallace. Amy is not the main protagonist, but she has the making of a hero...she's unselfish and although she too is disturbed by Dennis' actions, she doesn't make it about her; she keeps her focus on the large picture and doesn't let Dennis derail her the way Raymond becomes derailed from his job.
Even when Amy overhears Raymond and Kathleen bickering and Kathleen screaming that Amy's his "f**cking girlfriend"; Amy doesn't sink down to their level. Although we can sense that she is profoundly embarrassed by what she overheard, she stays on task and reports about VanStretch's death and is on the job and making sure the other officers are all right.
Amy also keeps the boat going smoothly even when she witnesseses Raymond's tantrum at work; she continues doing what she's doing in the investigation, although she is a tad frightened by Raymond's chair-throwing fit.
When she's injured near the end, even then, she doesn't consider revenge, she's mostly worried about Raymond and the rest of the LAPD being all right.
So, we have:
Hero: Amy Wallace
Anti-hero: Raymond Avila
Villian: Dennis Peck.
That's my take on the main characters in this film.
Roseanne + Jackie forever