A rookie is a member of the Black Hand who has participated in less than three missions. They are the newly initiated members of the Black Hand, formally known as mustajib ("deserving ones").
No matter what their age or level of experience in the Sabbat may have been, rookies are the lowest ranked members of any kamut or Watch, and must obey orders from any senior member of the Hand; in addition, they are not permitted to decline an assignment or challenge a tactical decision. For many Sabbat used to being the biggest badass in their pack, suddenly being reduced to the status of a shovelhead is hard to stomach, and there are those among the Hand who make sure that rookies get the message.
The rookies must prove themselves worthy all over again, and the bar has now been raised. What passes for badass in the Sabbat doesn't even merit a nod; the aspiring new Chosen must push himself beyond previous achievements and strive toward higher, tougher standards of physical, mental, and spiritual prowess in order to earn the respect of his new peers.
Rookies are often used to "fill out" a kamut, essentially being the extra guns (and sometimes the expendables) on a mission. While a rookie isn't yet trusted with mission-critical tasks, he may well be guarding the back of someone with that level of responsibility, who is trusting the rookie with her unlife so that she can concentrate on her work.
Rookies may also be given potentially hazardous assignments such as scouting ahead, covering a retreat, or guarding the kamut's escape route or vehicle. Many dominions look for opportunities to test a rookie's dedication and courage under fire, and consider a higher level of risk acceptable if it allows a "deserving one" to prove just how deserving he is.
Rookies who survive and perform well in their first three missions are informally initiated into full Black Hand membership by the dominion and the kamut they have served with. This ritual, known as the Blooding, is considerably less formal and serious than the one used to initiate a new member into the subsect.
While a Vaulderie and Blood Feast are traditional in addition to the formal announcement from the dominion of the new operative's advancement from rookie status, the nature of the actual "initiation" is left up to the kamut's twisted imagination (though in theory, the former rookie is supposed to survive the experience).