These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Seemed to be quite a popular character type between 2006 and 2009, with several examples including-
Joey Henderson, Ferndale Strangler, Murderer of 6 women.
Ethan Pierce, whose shady business practices include killing an old woman for her bone marrow, infecting Yvonne Jefferies with cancer and killing his business partner just to cover his tracks.
Don Lennox, Professional Hitman and murderer of Craig Valentine and attempted murderer of Justine Jones.
John Grainger, CEO of pharmaceutical company Scott-Spear, whose dodgy medication caused the death of Toni Warner and who was indirectly responsible for the murders of Huia Samuels and Craig Valentine.
Other examples over the years have included Oscar Henry, Dominic Thompson and Darryl Neilson.
Ensemble Darkhorse: Many characters over the years have become this, most notably Nick Harrison, whose original character was retooled from a drug-abusing badboy into a goofy good guy with a comedic side.
From the very first episode: "You're not in Guatemala now, Dr. Ropata."
Rescued from the Scrappy Heap: When he first appeared, Lionel Skeggins was a pretty obnoxious guy. Cue a romance with Kirsty Knight and a personality change to make him less annoying, and Lionel became a fan favourite for the rest of his time on the show.
Too Cool to Live: Several popular characters who've died over the years including Carmen Roberts, Steve Mills and more recently, Craig Valentine.