Continued from Wednesday.
Where people haven't found a way to defend against the machines, civilization has crumbled long ago. Surviving countries have stumbled upon a number of countermeasures: many machines have aquatic capabilities but none of them like salt water, which impairs their senses; many, especially older designs, are vulnerable to EMP. The most effective, however, is using other machines. Techniques exist for modifying their programming in order to turn them to human use. Even with modern improvements the process is far from perfect, though, and machines can go rogue if precautions aren't taken. One of the most important factors to keep in mind is that the programming changes can be fought, and most precautions center on ensuring that the machine doesn't want to escape (a steady diet of its owner's blood is extremely helpful). Machines will even fight attempts to undo these changes if the change was done right.
Handlers are usually picked out to begin training at a young age, based on initial psych evaluations, and spend years of further training and evaluations (with expulsions because of unsuitability, all along the way) before they are considered ready to be assigned a machine. They begin slightly off-kilter relative to other people but most, if nothing had been done, would have grown out of it. By the end of their training they are strange at best, inhuman at worst. You need to be, if you want to understand machines like you need to as a Handler. They are known to become more predatory in their relationships with other people, more like the machines that they spend so much time alone with. While it is extremely rare for a Handler to turn into a psychotic murderer, they often react even to minor physical assaults as if it had been a murder attempt and react to permanently disable their attackers (which can range from putting them into wheelchairs to actually killing them). Handlers also commonly suffer from sleep disorders, random bouts of uncharacteristic stubbornness, and extreme pareidolia, and display only faint body language (some even display none at all, and none have a smile that reaches their eyes).
Handlers typically have between one and three machines. Machines respond better when they have a stronger relationship with their handler (it is theorized that machines actually have some sort of latent need for something of this nature, given how quickly machines respond to acquiring- and losing- this relationship) and since machines often can transform in limited ways a Handler with only one machine is in no way worse off than a Handler with three if he knows what he's doing. Lack of support is made up by loyalty and dedication.
The American Initiative, located in South America, is the most secure organization in the world because machines don't like saltwater (even flight-capable machines usually find the Atlantic and Pacific Oceans to be too long of a trip over salt water) and the only pass northward is a perfect chokepoint. South America is the only continent save Antarctica which lacks "metal zones." While I don't usually go out of my way to curbstop the US in order to avoid "America Eff Yeah!" and instead just let the dice roll naturally and come up as they will, this setting is crying out for a curbstomp.
Long story short, US scientists were messing around with machines in the 50s, some escaped, and the country is slowly disintegrating. The United States (and some of Canada, too, since the British Empire isn't what it used to be*) is preparing for what will be either a last hurrah or a life-saving operation. As it stands, it cannot stay together for much longer- unrest is deepening and its rivals are beginning to notice just how many weaknesses it has been hiding.
This setting is a blend of Pokemon with Second Variety and Terminator, basically.
*It's hard to tell if the United States joined Canada, or if Canada joined the United States.