Oh fun, I'm interested.

Probably going to use the Concordat, anyone interested in doing a bit of a shared history?

In brief, they're a cybernetic heavy offshoot of <insert race>, born out of a civil war, fled to the stars. Probably still mortal enemies with the baseline <insert race>. These days they're largely caught up in their own projects, which are various ways of evading or confronting a Doomsday they're quite certain will come soon.