Wraeththu are a genetic mutation that evolved from Homosapiens of Earth. On their world they completely replaced the original population.
They are similar to human, closely resembling boys but androgynous enough in appearance to frequently be mistaken for female.
The correct gender pronoun instead of "male" or "female" for a Wraeththu is "har" (singular) or "hara" (plural).
Their primary difference from the human parent race is functional hermaphrodism - they are both male and female.
Their brain function differs slightly from human in that they are able to manipulate their own pranic energy to impressive degree, resulting (depending on the level of training) in psionic ability of a variety of types and strength. They have an extremely efficient metabolism, making it incredibly difficult to poison a har, although on the downside this also makes it nearly impossible for one to become drunk - even if they should want to.
They posess a genetic weakness wherein they do not efficiently generate this pranic energy on their own, and must restore it through sexual contact (aruna) with appropriately compatible beings. Physically, they are about as strong as an average human female.
The usually high level of energy within the individual har causes their eyes to glow in an eerie fashion, which is the most obvious mark of their alien nature. If a har's eyes are dim, they are probably beginning to suffer for want of energy. If they go for too long enough without it, they will eventually slip into lethargy, and eventually coma.
The Wraeththu genetic strain is an extremely agressive mutation transmitted via blood contact. Young human males, if exposed, can mutate into Wraeththu if they survive the process (called inception). Theoretically, this is how the entire human population of the parallel earth on which the species lives was replaced.
There is one Wraeththu living on Botany Bay, named Shyaa Farnell.