A strain of Corruption, the "slumbering" strain is a mutation of the Corruption virus that allows it to "sleep" within whomever or whatever is infected. A set of events and conditions "awaken" the virus within the host. These events are usually traumatic in nature.
When the strain awakens, it does not become fully active until one of two conditions are met:
1 - The infected successfully reaches a Nest or the "Motherland" (wherever Corruption has taken root).
OR
2 - The infected reaches an Echo. If the Echo has yet to "awaken" themselves, the infected will work to ensure the Echo awakens, usually by talking to them. Even being near someone infected with the slumbering strain will slowly affect the Echo until they awaken.
Those infected with the slumbering strain will not go through the more prominent stages of turning that the original strain creates. However, they will experience a series of more psychological symptoms that may persist until they have completely turned.
Triggering Events and Conditions: Usually, events that are traumatic or highly stressful in nature lead to the strain activating. If the host is ever suffering in any way, there is a high chance that if the seed is present, it will trigger a reaction and start the infection process.
The "seed": A unit of Black Venom that exists in the host's mind, body, or soul. It is very small, and multiple seeds will exist in an Echo. The core of the seed is the Black Venom itself and is wrapped in an outer layer of Innocence. As certain conditions arise, this layer erodes until the Black Venom itself becomes exposed. The amount of Black Venom, however, is very small, less than one nanometer. It will begin multiplying by assimilating fractions of the infected's DNA, mostly in the central nervous system. However, complete assimilation and transformation is not possible until the infected reaches a Nest, Echo, or the Motherland.
Symptoms of infection: Due to the more gentle nature of the slumbering strain, there are little physical symptoms, if any. The infected may experience weakness or sluggishness, paired with a low energy level. Other infected may experience a manic period, where they have heightened energy levels and increased strength.