Robert Buettner's wrote the three book series of Overkill, Under currents, and Balance Point. In Overkill The grezzen turn out to be the humans first contact intelligent species since the war fought in Orphanage series. The species are telepaths nad after wiping out the first two human colony attempts decided to contain us thinking we had developed on their cloud shrouded world.

I think the grezzen might make a good Traveller species.

Tom Rux