The ritual by which a wild tuk'ata bonds both mentally and emotionally with a humanoid, normally a Sith. However, some humans can bond with tuk'atas in this manner. The ritual involves going out into the jungles where the wild tuk'ata are, and basically waiting to see if a tuk'ata will "choose" one. To stress an important distinction: one CANNOT force this upon a tuk'ata. The tuk'ata chooses the humanoid, and initiates the bond through the ritual of the Blood Hunt, which they undergo together. (More on this later as I flesh it out, I promise.) After the ceremony of the Blood Hunt, the tuk'ata leaves his wild pack and adheres to his Companion, staying with him or her until death.
When the process of mentally linking with one another is completed, the animal is then able to communicate with his Companion, albeit in a somewhat stilted and strained manner. Tuk'ata otherwise have a very difficult time trying to communicate with humanoids, relying on body language for the most part to do so.
The only clan of the Sith to actively utilize the tuk'ata are the warriors, but not every warrior has the luxury of linking with a tuk'ata. Only the most elite of the fighters are allowed to do so, going to either Korriban or Korris'ian to enter the wild, and returning with (or without, as the case may be) their Companion. Those warriors with Blood Hunt Companions are highly regarded, and rise quickly in rank to supervisory positions over squads or battalions of Sith fighters.
[ March 20, 2006 12:31 PM: Message edited 3 times, lastly by Graysith ]