labingi

He has a lot of knowledge and a large vocabulary, so if born a Delta, Vila must have learned all that somehow, by perhaps being promoted to a grade he wasn't comfortable with. He does dislike responsibility and is easily bored, so I can see him buying his day down or back.

I suspect Avon of having earned promotion to Alpha through his high intelligence. He seems to care too much about grade, and he remarks at one point that everyone has the same chances he did.

Of course with B7 we have to extrapolate from off-hand remarks to fill in the many gaps.