For those of us intending on using the Witcher universe, this is a place to discuss its dynamics, specialisations and quirks along with anything that might come up with various characters interacting with it.

Edit: Since no one else is using this, I may as well pull some of the wiki articles across for quick reference. Be aware that while things are here, they're more likely to show up in flashbacks for Spitfire and Nightshade than on Aedrides.

Characters

Geralt

Geralt of Rivia (Polish: Geralt z Rivii) is a witcher and the main protagonist of the Witcher series by Andrzej Sapkowski and its adaptations (including The Witcher and The Witcher 2: Assassins of Kings computer games). Witchers are monster hunters for hire. They possess nearly superhuman abilities and are expert swordsmen.

Geralt is known also as Gwynbleidd (Elder Speech) meaning "The White Wolf", a name which was given to him by the dryads), as well as the Butcher of Blaviken.

Despite his name, Geralt does not come from Rivia: he grew up in the witchers' keep of Kaer Morhen in the realm of Kaedwen. In the interest of appearing more trustworthy to potential clients, young witchers were encouraged to make up surnames for themselves by master Vesemir. As his first choice, Geralt chose "Geralt Roger Eric du Haute-Bellegarde", but this choice was dismissed by Vesemir as silly and pretentious, so "Geralt" was all that remained, this name was chosen by Visenna (his mother). "Of Rivia" was a more practical alternative, and Geralt even went so far as to adopt a Rivian accent to appear more authentic.

Later, Queen Meve of Lyria knighted him for his valour in the Battle for the Bridge on the Yaruga conferring on him the formal title "of Rivia", which amused him. He is, therefore, a knight of Lyria, and not a commoner.

Vesemir

Vesemir is the oldest and most experienced Witcher at Kaer Morhen. He is a father figure to Geralt and the other witchers. He spends each winter in the fortress and sets off on the road when spring comes. He is an excellent fencer and has great knowledge of monsters.

He is the only one of the old witchers to survive the assault on Kaer Morhen, left for dead among the corpses of his fellow witchers. However, he was only a fencing instructor and thus did not possess the knowledge necessary to create new mutagens in order to mutate mere boys into witchers. Despite his age, Vesemir is robust and lively.

Triss

Triss Merigold of Maribor is a sorceress. She is called the "Fourteenth of the Hill" because she was erroneously thought to have been killed during the Battle of Sodden Hill. She is a friend of Yennefer and witcher Geralt, and unhappily in love with the latter. She took care of Ciri at Kaer Morhen for some time and is like an older sister to her. It was through her intervention that Ciri was not inadvertently given harmful hormones which might have negatively impacted her "womanly assets". She was a member of King Foltest's royal council along with Fercart and Keira Metz, as well as a founding member of the Lodge of Sorceresses.

She is a skilled healer and carries with her many magical potions, but she never uses them on herself because she is allergic to magic. She is also quite a powerful mage, certainly when it counts most.

Organisations

Witchers

A witcher (or hexer) is someone who has undergone extensive training and mysterious rituals (which take place at "witcher schools" such as Kaer Morhen) in preparation for becoming an itinerant monster-slayer for hire. Geralt, the central character in Andrzej Sapkowski's Witcher series and the subsequent games inspired by them, is said in the stories to be one of the greatest witchers; he is certainly legendary, but whether famous or infamous is more open to interpretation (and/or subject to gameplay, as the case may be).

Taken in as children when their innate abilities can only be hinted at, witchers-to-be are subjected to intense alchemical processes, absorption of mutagenic compounds, and other trials to make them highly versatile against their opponents (many of which possess superhuman speed, strength and/or other dread powers). These procedures ultimately mean that each fully-trained witcher is a mutant. The key permanent results of mutations shared by all witchers are

incredibly long lifespan (Vesemir is said to be at least a few centuries old);
sterility (which partially explains selection from the outsiders, as they cannot breed to pass on their traits);
tremendous resistance to disease (which functions in most cases as complete immunity).

Though it covers proficiency in basically any weapon that comes to hand, witcher training focuses on two primary tools - the Steel sword and the Silver sword - which are typically carried on the back, a blade for more mundane beings, and a blade for beasts of the supernatural. Most witchers are also frequent mixers and users of powerful potions, having developed a tolerance to their inherent toxicity but still limited to a few at a time (even one of their weaker brews will be fatal to an ordinary human). Finally, their formal magical training deals with Signs. Without extensive improvement and practice, these are mere tricks compared to what a sorceress can do, but they serve very well for someone with a sword in one hand to add a variety of edges to their efforts.

In general a Witcher is a formidable, and often overwhelming, opponent to more mundane races thanks to their strength, speed, minor magics and regenerative capabilities. However they are not infallible, as they can still make mistakes, take a mistep in battle against mundane men or supernatural demons, or be overwhelmed by sheer numbers and individuals who have the skill to match a Witcher. Though rare is the individual who managed to slay a Witcher out of skill rather than dumb luck or by ambush.

Though a witcher's eyes (see first glossary entry below) are one way to stick out, standard means of identification is the witcher medallion; this device aids in the detection of monsters, and no witcher would part with one willingly. (And of course, witchers are known for being 'hard to kill' - Leo Bonhart boasts a collection of three such medallions as proof of his martial skill.) The form of an individual medallion (head of a wolf, cat, griffin, etc.) indicates the school at which its owner was trained.

It is a common belief, even among witchers themselves, that they have no capacity for emotion. This may be debatable - and rather relative, considering the rigors of their training and the dangers they face as a matter of course. Perhaps they have simply never had the time (or exposure to society) to develop or recognize the reactions to mundane experiences that most take for granted.

Occasional references to witchers as 'non-human' are somewhat at odds with the original stories (in which Geralt only identifies witcher as a profession, never a race). There is certainly no official classification as such, and the relevant references (in the first game at least) are usually from Geralt identifying with the mistrust and/or hostility faced by elves and dwarves in human society. Likely it is used as a slur against the mutants, likening them to elves and dwarves.

Bestiary

Zombies

Zombies are animated bodies with no soul. In Sapkowski's books zombies are not specifically mentioned, only of the practice of necromancy, which is forbidden by the Brotherhood of Sorcerers. Necromancy is used for the purpose of extracting information from the (usually) recently deceased. The "interviewees" could be considered zombies. One example of the spell being used is when Visenna used it to briefly revive Manissa.

Wraith

Sometimes witchers must put to rest ghosts who haunt the living. Wraiths appear near cemeteries or in homes they inhabited during their lives. They usually have no memories and are guided strictly by hatred towards the living. May they rest in peace.

Barghest

These creatures, summoned by the Beast, haunt Vizima's outskirts. There are those who claim they are ordinary dogs transformed into monsters by some curse; others believe they came from the spirit world to torment the town's inhabitants. Packs of barghests appear out of the blue, in the middle of the night, to kill those who are late getting home.

Frightener

The frightener is a desert dwelling monster. It is nearly invincible, especially when controlled by a mage. Even witchers prefer to avoid fighting this beast if they can. Fortunately, this overgrown insect is sensitive to loud noises which deafen it and render it defenceless.