Beren Luthien

Suspected Nexus 7 prototype!
The Nexus series—genetically designed by the Tyrell Corporation—are virtually identical to an adult human, but have superior strength, agility, and variable intelligence depending on the model. Because of their physical similarity to humans, a replicant must be detected by its lack of emotional responses and empathy to questions posed in the Voight-Kampff test. Replicants became illegal on Earth after a bloody mutiny by Nexus-6s off-world. The Tyrell Corp./Rosen Assoc. discovered that the longer a Nexus-6 lived the more life-experience it gained. With these memories they often developed their own emotional reflexes, and the longer they lived the more independent and unstable their personalities became. Tyrell added a "fail-safe device" to Nexus-6 models: a built-in four-year lifespan to prevent them from developing their own "emotional responses". This was necessary for Mental-A models whose intellectual capacity at least matched those of their designers.

Transcript of audio file recovered at HQ Tyrell 1 ruins, time and date of recording unknown: XM-23451-A1-alpha (highly confidential: Alpha corp. board members only)

Tyrell: The facts of life. To make an alteration in the evolvement of an organic life system is fatal. A coding sequence cannot be revised once it's been established.
Roy: Why not?
Tyrell: Because by the second day of incubation, any cells that have undergone reversion mutations give rise to revertant colonies like rats leaving a sinking ship. Then the ship sinks.
Roy: What about EMS recombination.
Tyrell: We've already tried it. Ethyl methane sulfonate as an alkylating agent a potent mutagen It created a virus so lethal the subject was dead before he left the table.
Roy: Then a repressive protein that blocks the operating cells.
Tyrell: Wouldn't obstruct replication, but it does give rise to an error in replication so that the newly formed DNA strand carries the mutation and you've got a virus again. But, uh, this-- all of this is academic. You were made as well as we could make you.
Roy: But not to last.