Sleeper agent
A sleeper agent is a spy who is placed in a target country or organization not to undertake an immediate mission but to act as a potential asset if activated. Even if unactivated, the "sleeper agent" is still an asset and is still playing an active role in sedition, espionage or possibly treason by virtue of agreeing to act if activated. Sleeper agents are popular plot devices in fiction, particularly in espionage fiction and science fiction. This common use in fiction is directly related to and results from repeated instances of real-life "sleeper agents" participating in spying , espionage, sedition, treason, and assassinations. In espionage. In espionage, a sleeper agent is one who has infiltrated into the target country and has "gone to sleep", sometimes for many years. The agent does nothing to communicate with the sponsor or any existing agents or to obtain information beyond what is in public sources. The agent acquires jobs and identities, ideally ones that will prove useful in the future, and attempts to blend into everyday life as a normal citizen. Counter-espionage agencies in the target country cannot, in practice, closely watch all those who may possibly have been recruited  some time before. In a sense, the best sleeper agents are those who do not need to be paid by the sponsor, as they are able to earn enough money to finance themselves, averting any possibly traceable payments from abroad. In such cases, it is possible for the sleeper agent to be successful enough to become what is sometimes termed an "agent of influence". Sleeper agents who have been discovered have often been natives of the target country who moved elsewhere in early life and were co-opted (perhaps for ideological or ethnic reasons) before returning to the target country . That is valuable to the sponsor as the sleeper's language and other skills can be those of a native and thus less likely to trigger domestic suspicion. Choosing and inserting sleeper agents has often been difficult, as it is uncertain that the target will be appropriate some years in the future. If the sponsor government and its policies change after the sleeper has been inserted, the sleeper may be found to have been planted in the wrong target. In fiction. In fictional portrayals, sleeper agents are sometimes unaware that they are sleepers. They are brainwashed, hypnotized, or otherwise conditioned  to be unaware of their secret mission until activated. Examples of such stories are: