Thread: How the Special Infected created

Note: this theory is mainly about BOOMERS, which I consider the most important of all the special infected, and below you will find out why. Without them, there would be no transmission of the "special infected" strains of the zombie virus.

Clearly this virus is incredibly fast spreading and has incredible regenerative properties, and has the power to completely take over a human and convert it to something else. It must trigger the "anger" or "rage" center of the brain, causing the infected to attack without thought or fear.
The common infected are easy to explain (a basic air born virus), but the special infected are another case entirely. I believe that this virus is fast mutating also, that is why there are so many variations. The basic virus is the one that creates all the common infected, but then after it was spreading and mutating, it began to specialize, with certain strains of the virus only infecting certain types of humans. These strains were more evolved, thus allowing their hosts to be more intelligent and have more "quirks".

The boomer is a very interesting one. It is the only virus that appears to affect males and females (hence the boomer and the boomette). The humans, before infection, were hugely obese and unhealthy. When the virus hit, the liver/gallbladder/other digestive system organs were effected the most. My theory is that the boomer contains in its large body a continuously mutating form of the disease, and also contains ALL the other strains. The boomer is a "carrier" for all the special infected strains. The other strains don't affect the boomer itself because each of the special infected strains are evolutionily tailored to infect a certain type of human.
The boomer must also have its brain messed with by the virus. When it sees survivors or "danger" at a close distance, it pukes as a reflex, not on purpose. It then has a "fight or flight" response, which is why sometimes it scratches you and sometimes it waddles away

This would also explain why there are so many special infected, because if all the strains for the common infected were air born, the disease would mutate too fast and each special infected would be vastly different. Thus, boomers would have to puke on a common infected or a uninfected human to turn them into a special.

Note: the only reason the L4D and L4D2 survivors aren't infected is because they might be carriers of the disease or immune, and wouldn't be affected.

Interesting idea of the Boomer

In my theory about the Infection, I think that there are only two main Sub-strains that exist despite the many different manifestations. The theory is definitely not perfect, but it's the best one I can think of at the moment

Boomers, Smokers and Spitters belong in the first, because most involve the over- secretion or overgrowth of something involving the digestive system. Smokers emit gaseous 'smoke' and have tongues, Spitters have their stomach acid, and Boomers have bile.

The second sub-strain creates Hunters, Tanks, Chargers, and Jockeys. This involves the musculo-skeletal system, because it involves induced growth of muscles and bones.

And now onto some of the Infected!

Boomer: I agree with the L4D wiki that Boomers might be simply heavy people that got Infected, and that it might be using their fat stores to produce overproduce bile. My theory as to why this happens is the bile is a big attractant to Hordes, and this spreads the Infection as the Horde is the main vector (through biting and scratching) to transmit disease.

Hunter: Firstly, I don't think parkour is necessary at all to create Hunters. If it were needed, Hunters would be extremely rare and only found within cities, and it would not explain why they are one of the most common Specials. And I do find it extremely unlikely that parkour suddenly became popular enough prior to the Infection to explain all of them, so I might try to give an idea as to why there are so many and why they are wearing their particular clothes like they do...
Hunters are simply athletic guys that turned into Specials once Infected. The reason why they are all wearing hoodies and sweatpants (the said-to-be clothes of the parkour) is that hoodies at least are extremely common anyway, and don't restrict movement. Also Hunters likely use the cowl to protect their destroyed eyes and funnel their screachy 'sonar,' which explains why they seem to prefer hoodies so much and will keep the cowls on and up even after tearing the rest of their clothing.
And why they have tape on their clothes? The tape was likely put on early after the Hunter turned but before he became more like an animal. Duct tape can be found almost anywhere, and it would be a widely available, simple, and easy solution for binding down loose clothes that are catching on everything.

Smoker: I agree with the Wiki that these guys are likely to be cigarette smokers that happened to get turned into Specials. So there isn't much I can say about these.

Tank: He's likely to be an anabolic steroid abuser when he got Infected, which explains why he's not common and why he's often extremely angry ('roid rage.') The Infection's mutation effects were likely boosted from the steroids still present in his system and already huge muscles, and his aggression would be heightened even more then normal since his brain already is affected by the 'roids.