Yay for interests! Shelton is in the middle of an icepocalypse, and so I will have to get him officially on board in a few days. He's set to hopefully have power back by like next week.
As far as the walking dead goes, every single human on earth is infected with a disease (as a biology major I'm basically forced to explain evolutionary microbiology to you guys). It seems to me that the virus in the show is a defense mechanism of the human race as a whole, an evolutionary trait that has developed over the last several hundred (perhaps even thousand) years in response to the fact that humans are the leading killer of humans. There is a vast overpopulation of Homo sapiens sapiens on earth, and with overpopulation eventually comes an ecological fallout, due to lack of resources (anything from the air we breathe to the food we eat, to even clean water). So, our bodies begin to open up to host new diseases, culling out those who aren't particularly strong enough to fight off such. This is where patient x comes from, in this case. It has never been explained exactly where or how this person came about.
For all we know, it was some old fart that died, and suddenly the virus was evident. It appears (which really isn't as realistic as I would like) that the virus flipped on like a light. We know that it is happening all over the world (in TS-19, it was mentioned that the Paris CDC was the first of the Government Agencies to fall, and it struck fear in all of the scientists, who then began panicking, and several committed suicide, realizing there was no way out.
It appears that some people are simply resistant to the virus (like the survivors) but as with a lot of different pathogens and bacterium on our skin (staph, MSRA, etc.), the strain that is punctured through the skin is a lot more prevalent, robust, and quick evolving than the slow incubating virus inside of us. The virus inside of us uses us as a vector, of sorts. When our body dies, that's when the virus takes over, standing us up and using us as a sort of vehicle. It walks us around and because it takes control of only the Cerebellum (balance, motor skills, and coordination), and the spinal chord (chewing, swallowing, and parts of the pharynx), we come back as dead, but very slowly decaying corpses. Due to the lack of body heat, and the lack of blood flow, and natural body decay, our bodies go into a sort of slow burning rot, that can last for months (and in some cases, due to winters, maybe years).
There are three ways that someone can come back as a walker (that we know of - I'm still iffy about people getting blood into wounds). Those things are: a bite (as stated above, saliva vs blood...two different strains), dying of natural causes (or really any causes that don't destroy the cerebellum), and scratches (for some reason, their blood mixing with ours deliberately seems to cause us to turn).
I don't expect you to have a grasp on all of this, really. I just used what I know to explain it. However, I expect that if you're going to make walkers, or if you're going to throw a character into a situation, be realistic. The Walking Dead created zombies very similar to the Max Brooks zombies (the BOOK World War Z and the Zombie Survival Guide). They are slow, but they are incredibly strong. They do not feel pain. So, they do not feel fatigue. This means that while me and you can't grab someone with our fingers and crush their skull, a walker might be able to, due to the lack of muscle strain.
If you remember (or have seen it), Dale was eviscerated in season 2 by a walker. It seemed easy because it was. Where I'm going with this is, your character would have a lot of trouble fighting off a thousand hands if he was in the middle of a herd of walkers. It only takes one to get a good hold on him, and he's done. So, be realistic.
Now that I have ranted, and probably made my Shelton proud of me lol I will leave you guys to it.
If you want an OOC, right now, I can post one sometime tomorrow. If you want to wait a bit longer, we can. :)