As you might gather from the name, Zoom hails from a particular school of supervillainy. As Bizarro is to Superman, or Venom to Spider-Man, so Zoom is to the Flash: The Evil Opposite (or Counterpart, if you want to go by tvtropes.org's classification), the manifestation of the hero's abilities twisted to evil ends. It's all the more potent with the original Zoom in that he was the Barry Allen Flash's exact double.
As a kid reading comics, The Flash was one of my favorite titles. Like most kids my age, I ran everywhere. What kid wouldn't pick up on the fantasy of running so fast that nobody could see him? Kids like speed. Some of them never grow out of that and hit the NASCAR circuit or something.
Like all superheroes who last longer than three issues, the Flash had an impressively large rogues' gallery (in fact, that's what they call themselves: "The Rogues' Gallery", or just "The Rogues" nowadays). They were a band of gimmick villains with self-explanatory names like Captain Cold, Heat Wave, or the Weather Wizard. They would joust with the Flash using Central City as a backdrop and game board, seemingly engaged in an endless game of trying to both outwit the speedy hero while still getting away with a big payday of loot. In those days of the 1970's, it all felt like a game, cops and robbers with superpowers.
Except for Professor Zoom. He was coming from an entirely different place than the rest of the Rogues. He just hated the Flash and wanted him dead. Even with the lighter fare that was the monthly comic back then, you got a vibe from Zoom that he just wasn't playing.
All of that came to a head in the 1980's, a while after I had put comics out of my life for a time when, after the villain had engaged in a campaign to pick apart the Flash's life piece by piece, the hero had to kill Zoom in order to save the life of a loved one. And even then it wasn't over, as the Flash ended up being tried for the villain's murder, events that would lead to his own death in the 1986 groundbreaking series Crisis on Infinite Earths.
I think the death of Professor Zoom served as a precursor to the darker, more nihilistic take on superheroes that was formally ushered in by the likes of Frank Miller's Batman: The Dark Knight Returns and Alan Moore's Watchmen. After all, if a sunny, gregarious, fun-loving hero like the Flash could be driven to take a life, where does that leave the rest of the fraternity?
In a way, Zoom's sacrifice of himself had not only ultimately destroyed his foe, but served the concept of heroism itself an almost mortal wound. The decade would grind on into what Harlan Ellison termed "The Adamantium Era", where "heroes" were often largely distinguished from villains by the fact that they'd at least try not to take out so many innocent bystanders.
But you can't keep a good bad guy down, and thanks to the fact that Zoom came from the future (don't ask me to go into detail; believe me, nothing guarantees a headache faster than trying to break down a time travel story), he's popped up a couple of times to plague Barry Allen's successor as the Flash, Wally West.
Still he was, in the end, very definitively dead, and even comics writers who have put a revolving door on the afterlife (see Grey, Jean) find things like a broken neck and the body laying at the hero's feet a tough one to walk back from.
So they gave Wally a Zoom of his own. And boy, is he a piece of work.
Unlike his predecessor, Zoom doesn't seethe with Flash-hatred. Quite the opposite, in fact. He wants to help. He wants to make the Flash a "better hero".
So what makes a better hero? In the mind of the new Zoom (who eschews the honorific "Professor"), nothing but tragedy. In his mind, the current Flash hasn't suffered enough to care about preventing the suffering of others. Zoom aims to fix that. He's the much- and rightly-criticized "women in refrigerators" writing device given a face, and he's meant to be scary as hell.
So why am I wearing the colors of these psychos? Because, to paraphrase Christian Bale in Batman Begins, they scare me. And I want my opponents to feel that same dread. ;-)