Fixers

Fixers are intermediaries between corporate interests and shadowrunners. Since shadowrunning is, by definition, an extralegal profession, middlemen are often hired to either connect corporate interests with runners fit for the job, or in some cases to fully run jobs that don't need oversight. These connections also put fixers in the position to be information-brokers, people who can buy and sell information through their networks.

Career

Qualifications

Unlike runners, who are only really expected to be competent in a firefight, fixers are generally expected to have a few qualifications before being hired. A good repuation is crucial, as is a strong network of contact to call on; a fixer lacking the former is untrustworthy and one lacking the latter is useless. As such, a fixer with a background in either corporate or mercenary work is usually expected, at least until they get a reputation as a fixer. Rarely do people move up to being a fixer from being a runner; the associations and baggage of being a runner are usually disqualifying for being a runner. 
Although the job doesn't require negotiations per se, a fixer is also generally expected to be socially competent, or at the very least discrete. Mr. Johnsons generally don't like meeting with a fixer who can't speak their language and runners tend to be on guard around fixers that are too over-the-top.

Payment & Reimbursement

Generally speaking, when a Mr. Johnson is looking to hire a group of runners they will have to declare two payments; the first is the finders fee given to the fixer, and the second is the completion fee given to the runners. Older groups used to package the finders fee in with the money give to the runners, but this caused conflicts where runners and fixers tried to screw each other over. Nowadays standard practice is to keep the fees separate to ensure no conflict of interest; regardless of how the run turns out, the fixer gets their fee. 
Since this practice puts the Johnson on the line if things do work out well, fixers are incentivized to maintain a good reputation with corporate interests. If a fixer is known to hire duds who fail to complete the jobs they're given, that fixer might end up blacklisted from further jobs.

Perception

Purpose

Fixers serve as the point of contact between shadowrunners and the rest of the world. They are primarily used to be the middle-man between corporate interests, who don't want to be associated with runners, and the runners themselves. However, in many cases they may also end up being the general contact for a group of runners, regardless of prospective employers; a fixer might become the "face" should their runners consistently use them as their point of contact, even when their employer isn't a corporate interest. 
Fixers also regularly take up roles as information brokers for a wide variety of clients. A crucial part of a successful career in the industry is to have a strong network of contacts, which means that fixers are some of the only people fully in the know about the corporate world. This makes the exchange of information (or in some cases the explicit refusal to exchange information) highly lucrative, sometimes even moreso than being a middleman. The latter is still a hard requirement, however; no Johnson will maintain a fixer as a contact if that fixer doesn't aid them with jobs consistently.

Social Status

As far as the public is concerned, fixers might as well not exist. Whereas shadowrunners were exposed to the public due to their work and sensationalized media, fixers have neither exposure and are therefore generally unknown. This is done on purpose, as a fixer known to the public as a fixer loses the discression that makes them valuable to corporate interests. Many fixers will set up "consultancy firms" or "consultancy unions" which act as a cover for their work, allowing them to fully disappear under the radar if a corporations actions are brought to light.

History

Fixers are arguably an older profession than shadowrunning, depending on how the profession is viewed. Before shadowrunning became common practive, fixers were still used as a point of contact for mercenary groups. Although mercenary work was legal, and therefore above board, most groups still hired people specifically to act as middlemen, whether for their social skills or for their previously established connections. As shadowrunners supplanted mercenaries in the '20s, fixers made the transition to working with the new environment. 
This change came with an increased demand for discression on the part of fixers; if a fixer is known to work with runners, it defeats the purpose of going to a middleman. This demand jumpstarted the practice of fixers being employed by some third-party (either a specific union, an independent firm, or a division with a corporation itself) to act as a cover. Rather than "meeting with a fixer to hire runners" executives were instead "consulting with a professional to solve a problem."

Type

Illicit