[It was my plan to post this yesterday but I became really, really tired after doing some writing in another project. Before I noticed, it was past midnight and it was time to move this to another another day.]
If you have ever heard the phrase “We back tracked them using their e-mail proxies in order to break the encryption they used on their port routing protocols” then you are hearing a techie talk. Any time that a character uses the word “protocol” or any other general technology word, then the use of the techie trope is being used in order to progress the plot.
Techies are, basically, the technology of the show speaking through the mouthpiece of a human. They are used to explain things that would be complicated to most of the viewers of the show (Such as checking e-mails). Anything that a computer can do, such as basic searching, to more advanced thing such as breaking encryption are the jobs of the techies on a show.
Since many people fear technology, techies are often shown to be the odd character in the show. Techies are the strange and weird of the show because, as I said earlier, they are metaphorically the technology themselves.
Some examples of techies in recent shows include:
Abby from NCIS. Playing up the fact that many people who are into technology are also strange in themselves, she is shown as an often overly happy goth.
Greg Sanders from CSI. He is the go-to evidence person for the early seasons of the shows before “graduating” into being an investigator himself. His weirdness is played up in the fact that while being a scientist, he still believes in many occult things. (Because those two theories are impossible to have at the same time. Obviously.)
Dr. Walter Bishop in Fringe. He is the quintessential “mad scientist”. Having scrambled his own memory (that’s probably a spoiler, but I don’t really care), he generally has tastes and wants in places where people don’t expect it. (Such as, you know, wanting pudding while looking at a person who was reduced to a puddle.)