Magic effects are accomplished through contracting with a symbiont. You can only take magical abilities as advantages – there is no “magery” advantage in this setting. Most spells can be converted into advantages fine – see the “Powers” book.
The symbionts interact with their hosts in a variety of strange ways – some grant the ability to take on alternate forms, others grant the ability to control or produce fire. The symbionts are normally fairly specialized – they have specific capabilities tied to a central theme. They do however also carry a physical and psycological effect on the host as well. These effects are as unique as the symbionts themselves. Some contractors have to eat more or sleep more, some eat or sleep less. Some gain darkvision or nightvision, some can see other spectrums of light entirely. Some grow stronger, others weaker. Some age faster, others age slower. The effects are entirely unpredictable until the symbiont synchs with its host. The contract is always agreed upon prior to this synch, so there is some aspect of a risk to creating a contract.
Payment of the contract must be paid as soon as the contractor is out of immediate danger (as judged by the GM) – delaying this payment has penalties in the form of FP and HP loss! A contractor who doesn’t eventually make his payment will melt into a pile of goo.
Nobody really understands the motivations of the symbiont. They seem content to carry on as they are now.
Daemons are contractors who had no choice in the matter. They are generally feral. Occasionally there is a Daemon who maintains sapience, though the symbiont is in control (or sometimes the host and the symbiont fight back and forth for control). Nobody has yet been able to find a way to separate a Symbiont from its host prior to the hosts death, except the symbiont itself.
The lifespans of symbionts are unknown, as neither the birth nor the death of any have been witnessed.
Contractors are required to be registered with the government, but rarely do they as there is no known means of detecting one unless they make a display of their powers.