Captain Scarlet's main antagonist is the Mysteron agent Captain Black, known for his deep bassy voice. But the thing is, Captain Black used to be on Captain Scarlet's side, until the Mysterons got him... he had his entire personality stripped and his mind destroyed so he could become a voice for the aliens. Fridge Horror? Definitely. Or worse: maybe they didn't destroy his mind, and he's seeing and hearing everything they make him do.
It is outright stated that Captain Scarlet still feels pain; go back and see how often he dies (about once an episode), then count how many of those are slow or unpleasant deaths. Brr...
All evidence seems to point towards the original human Captain Scarlet being swiftly forgotten (or at least rarely ever brought up again) and his life acquired/stolen by his duplicate without any complaints at all. Was he ever given a medal for dying in the line of duty? A funeral with honors? Do any of his Spectrum friends actually ever visit his grave seeing as they have another Captain Scarlet working alongside them every day? Does he even have a grave given how badly his body was immolated by that crash and as such did anyone ever bother to put some flowers by the side of that road in respect? So many disturbing implications and so few answers.
It's easy to feel cheated by the All Just a Dream ending of "Attack on Cloudbase"... until you realise that the whole episode makes far more sense as Symphony’s nightmare, showing all her worst fears. Think about what happens: Captain Blue admits his love for her, only to die when Cloudbase goes down. Rhapsody, one of Symphony's closest friends, dies a horrible, violent death, and then Scarlet — Earth's biggest hope against the Mysterons — is Killed Off for Real. Throw in all the surreal elements, such as the glowy Mysteron flying saucers, White telling Scarlet to get his hair cut, Captain Black as Doctor Fawn's assistant, Magenta's seeming inability to count... the whole thing plays out like a mad dream of someone who's really feeling the stress of the War of Nerves.
It is implied that it was the mortal injury combined with Scarlet's cast iron force of will that brought him back to our side. It is possible that Scarlet isn't unique in this certainly, but not likely to be a common occurrence. This very easily crosses into Fridge Horror territory as how many of the mysteron duplicates that Spectrum killed over the years had the potential to be captured and rehabilitated but were not given the chance?