X-Men
Mutants
Human Mutants have many distinctive traits in regards to biology, physiology and genetics from other humans. Mutants can have wildly varying biologies depending on the nature of their mutation. Mutation is caused by the X-Gene in the mutants' DNA. Mutations normally manifest themselves during puberty, often as a result of a traumatic event. Some mutants exhibit their mutations at birth, however, while others do not manifest their powers until adulthood. Secondary Mutation is a phenomenon in which an existing mutant gains additional powers, or a change in their appearance due to a second mutation. The mutants can be divided into multiple categories, regarding to their origins, genetic status, powers (e.g. Omega Level Mutant), etc.
While in most Marvel universes the X-Gene was presumably a result of modifications on early man by the Celestials, in the Ultimate Universe the X-Gene is a creation of the US government weapons project in Canadian facilities. This reality's Wolverine was the first of these mutants, and was called the Mutant 0. This mutation is similar to a virus, infecting the population slowly and turning them into mutants.
Xavier Institute
X-Men
The X-Men are a team created by Professor Charles Xavier as a response to the emergence of naturally occurring super-humans known as mutants among the baseline human society. Seeking to promote his dream of peaceful coexistence between mutants and humans, Xavier trained his X-Men in the use of their powers at the Xavier's School for Gifted Youngsters, training them to become defenders of a world that hates and fears them. Over the years, the heroes of mutantkind found their mission constantly endangered by both reactionary humans and fanatic mutants.
Xavier Institute Student Body
This mansion, located at 1407 Graymalkin Lane in Salem Center, New York, had been inherited by Charles Xavier and has been in his family for a 100 years.
The saying of the Institute is 'Mutatis Mutandis', which is Latin meaning 'with those things having been changed which need to be changed'.
Located at 1407 Graymalkin Lane in Salem Center, New York, the Xavier Mansion has been home to the X-Men since their inception, and has always been a school and safe haven for any mutants in need. The mansion has been the subject of damage due to battles and has even been destroyed twice. Once during the events of Inferno, in which Mr. Sinister destroyed the whole mansion, except for its underlying basement (which included the X-Men training-ground; the Danger Room). After some time the mansion was rebuild with funds from investors in Xavier's school.
The mansion was later badly damaged during an attack by a former instructor, the mutant known as Xorn, who was posing as Magneto. The end of the battle left long time X-Man Jean Grey dead at the hands of the mad mutant. The mansion got a large renovation after these events, in which almost nothing of the original school could be rebuilt. The school was now in the shape of a giant "X". In the middle, there was a courtyard, where mutants could pay respects to the deceased Jean Grey.
Mutants could train their unique abilities in the a training-room known as the Danger Room. There also resides other high-tech equipment such as Cerebro, a mutant tracking device utilized by telepaths like Professor X. This device is in a highly-secured room and is available for only select few people such as Charles Xavier and the Stepford Cuckoos
- X-Men Player Characters: A more direct link to the current PCs, with less flavor text and pictures.
Antagonists
Mutants in general, and the X-Men in particular, face a different type of enemy than other metahumans. First of all, the primary enemy of the X-Men is not a greedy plunderer, or an insane tyrant, or an omnicidal alien. The true enemy of the X-Men is Hatred. Hate and Fear of the unknown, the different.. the mutant. Protecting mutants from persecution and misunderstandings, and protecting humanity from the depredations of Evil Mutants, the X-Men stand united against this one pervasive adversary.
More interestingly, the X-Men and most of their rivals tend to share cultural and genetic origins. The Brotherhood of Mutants, the Mutant Liberation Front, and several other people whom the X-Men have clashed over for noble reasons over time, have time and time again sided with the X-Men when the threat came for their race as a whole. Sentinels. Friends of Humanity. The Phalanx. The one unifying tread all mutants have, their need to survive past being the subjects of hate or convenient scapegoating.
As such, very few 'Evil Mutants' actually exist that have not, at one point, sided with the X-Men against their shared common enemy. This is why over time, practically everyone of the X-Men's enemies have worn an X somewhere on their costume, or have been otherwise associated to the Xavier Institute.
Evil Mutants: The most likely enemies of the X-Men. These are mutants who are opposed to the X-Men's Dream, or who have their own reasons to dislike humanity. These are terrorists, or simply criminals who don't care what their actions do for mutant rights. Not all of these are mutants, however, but they are often mistaken for mutants.
Hate and Fear: The truest enemy of the X-Men. Hatred and Fear, weaponized, or given form or a voice, the enemy of the X-Men's Dream in the purest form. Bigots, profiteers, industrialists, hate-mongers and other such monsters who oppose the idea of peace between humans and mutants.
The World at Large
The World of the X-Men, also known as Earth-616, has many other superheroes, and other races, similar to, or offshoots of Mutantkind, or Humanity. While it is generally comparable to the real world everyone reading this is familiar with, massive leaps in technological advances have been made, by Mutants and Humans of note. Living Islands, quaint European hamlets doubling as World Superpowers, an isolationist African nation which gave the cure to Cancer.. it is not simply 'our' world but with Mutants in it. However, by and large, it is. Most of this world does not affect the situation or plight of Mutants, and as such, the X-Men interact with it peripherally. There are, however, things that affect their existence.
- Government Agencies: The governments of the world have to take Mutants into account. For good or ill, countermeasures to Mutant terrorists have to be prepared. Threats, both from within and without, must be accounted for, by individual countries, as well as by the world community. These groups will just as often work alongside the X-Men as they will butt heads with them. Whatever the situation, no expectations should be held.