Greys are genetically engineered AI drones/slaves/pilots for the master reptillian race
Greys have in part human DNA
Earth is a farm
The "reptilian" alien is what we would consider demonic, though their purpose in life is not to cause suffering, they are selfish, instinctual, have no empathy, and reject spiritualism.
Their life is very long, they can live for thousands of years.
Their communication, like reptillians on earth, is mostly silent. They can communicate a lot through body language, in fact so much they are capable of telepathy.
And since they're not empathic, the telepathy is also primordial: they can communicate and induce basic emotional states: fear, flight or fight, paralysis, etc...
Your mind completely naked to them. If you meet one, they would paralyse you with fear. A look in their eyes will hypnotise you to sleep. That's what they're capable of.
They do have a sense of "right" and "wrong", they're not evil, they're just not very suitable for human companionship. Not at all.
They harvest human DNA for their clones and other experimentation. They also breed us into a direction that is suitable for them: more intelligent, longer lifespan, more docile.
It is them who made us walk up right.
Their species is hard to locate or define, since they're masters of genetic manipulation, many of them will also undergo radical transformation during their lifespan. They can have unique and variable appearances. From classic reptillian, to draconian, to insectoid, to humanoid, even crustacean, orthologic and botanic features can be adapted by them.
They have a similar role and level of power as the Precursors, though reptillian origins are biological and that remains their basis.
I don't know if they have competing enemies or if a more powerful species exists.
Not sure if we should hope for that, since we're not under tyrannical oppression and actually being looked after and improved.