A Keeper is the central focus of a telepathic circle, they are the one who receives the amplified energon flows produced by each member of the circle and braid them into a single flow to be tuned and amplified by their matrix. The Keeper is considered the "head" of the circle and controls what the amplified ernergons are used for. The ability to channel these powerfull energies is a genetic manipulation that is similar to the Hastur gift, for this reason those with that donas made excellent and powerful Keepers.
It appears in the past before and during part of the Age of Chaos male Keepers were the norm. It was Varzil the Good who fought against tradition and took a female apprentice Ashara . It appears that after this Keepers started to become exclusively women due to they produce more a positive energon flow and they generate them younger and keep them longer.
During the darkest age of laran Keepers were sheltered and kept virgins. Virginity was considered essential for a keeper and that immediate death would happen if they were not. The training for young girls was very vigorous and some did not survive it. Keepers were trained to avoid any physical contact and even have deadly reactions when they were threatened with rape. The belief in this superstition was so strong among Darkovan people that Cleindori Aillard was murdered by fanatics.
Being a Keeper is a very dangerous position that calls for incredible concentration, power and skill. In order to focus multiple energon flows and to weave them into a singe matrix means a Keeper must allow this flood of power to go through his/her body or more precisely through their channels.
The trouble is these channels are shared between energons and "sexual energy", this is why threshold sickness occurs during puberty. The channels must be completely open in order to allow the energy to travel through them, if a Keeper has any sexual activity (even non-physical) these channels will not be completely free and this can cause some overflow. The results can be very serious wounds and even death.
This is why Keepers were originally trained to not attract desires and attention and not to even feel them. Active Keepers remain celibate and strictly chaste, they must remain distant from others even their own circle members, even though working in a circle is very intimate and brings its members together.
Keepers are always garbed in red robes, this is to reminder to all that they are never to be touched.