Betazoid

The Betazoids are a humanoid telepathic race from the planet Betazed. By the 24th century, Betazoids were an integral member race of the United Federation of Planets. (TNG episode: "Haven").

Physiology
Externally, Betazoids are nearly indistinguishable from Humans physically. Their sole distinguishing physical characteristic that the irises of their eyes are completely black.

In addition, their rapid eye movement (REM) sleep frequency is different than for most humanoids.

Betazoid childbearing is similar to humans, except the normal gestation rate for Betazoid females is ten months rather than nine. Betazoid women are not considered to be "matured" until they at least reach their forties in equivalent human years, which coincides with the timing of the female Betazoid "Phase." At this point, a female's sex drive quadruples or more.

Mature Betazoids can also suffer from Zanthi fever, that causes the Betazoid to lose control over the projective aspect of his/her empathy. That can result in people around that Betazoid acting as if they'd experience the same general emotional state as him/her, though they are directed by their own subconscious desires, fears etc.

Betazoids can reproduce with Humans, although this often dilutes the telepathic abilities of the offspring. The children of such a union often develop empathic rather than full telepathic abilities, though they can still communicate telepathically with their Betazoid parent and a bonded mate.

Telepathy
As all Betazoids are telepathic, they usually do not need to vocalize their thoughts to one another in order to communicate, but can do so for the benefit of offworlders. It is a natural ability, and likewise the strength of the skill varies from one to another. The telepathy is not inborn but almost always comes on with adolescence. There are also cases of over-empathic abilities, and those who suffer from such extremes must be counseled and trained to avoid insanity, but are almost always affected throughout their life.

Betazoids are actually uncomfortable around those, like the Ferengi and Breen, whose minds they cannot read. Similarly, the minds of animals can be a bit frightening to them, and they tend to prefer smaller animals.

The Betazoid brain contains the paracortex, their telepathic lobe, which is highly capable of recovery from injury, and includes the "metaconsciousness," or a trauma filter. Psilosynine is the neurotransmitter involved in telepathy.

Their empathic/telepathic contact leads to a natural trait of complete honesty, somewhat troubling to outworlders when practiced fully.

Culture
Betazoid society tends toward more formal and elaborate traditions and ceremonies than most cultures in their present evolutionary stage. Some of the rites often make the more conservative Federation offworlder uneasy at first, most notably the traditional wedding ceremony in which no clothing is to be worn. Though there are no official gender-based restrictions in place within Betazoid society, women have traditionally held many positions of authority.

Betazoids practice an old style of marriage arrangement called genetic bonding, wherein children are promised to each other for marriage later by their parents. On the same note, Betazoids are known for their ability to love more than one person without losing their ability to love their mate, nor are they bound by their marriage customs. Because marriage is a celebration of the act of love to Betazoids, the wedding ceremony itself is traditionally conducted in the nude.

History
Betazed has enjoyed a relatively untroubled history for the last few centuries. This peaceful existence came to a halt in 2374, when the Dominion invaded and occupied the planet.

The Dominion's desire to do experiments with telepathy played a big part in their decision to annex Betazed. The Dominion had control of Betazed for over four months. In four months, tens of thousands of Betazoids disappeared. Groups were being rounded up at an alarming rate. Jem'Hadar were rounding up the most talented telepaths for use in experiments conducted by the Cardassian scientist, Crell Moset.

Crell Moset made the Jem'Hadar telepathic, but they contained a fatal flaw. Because the Jem'Hadar mind processes emotions very differently from other humanoid, the ones that were made telepathic suddenly found themselves bombarded empathically, with no way to close off their new perceptions. Immediate, fatal seizures were the result. It also effected unaltered Jem'Hadar in close proximity. This same flaw made the Jem'Hadar vulnerable to projected emotions. It made them catatonic for one hour or so.

Betazed was freed by taking advantage of this flaw by using invasive empathy on the Jem'Hadar. The strain killed 40% of the Betazoids performing the technique, and some of the Jem'Hadar went berserk and killed each other, but most were catatonic.