So looks as if the two prospective buyers finally bought.

After purchasing Onyx from the slave market, the eagle offered him a place inside the merc company he works for. Onyx, wanting to get out of the cage and feeling a sense of curiosity about the mercs and his new companions, accepts the offer.

A few days later, he gets a new look, a new weapon, and a new purpose in life.

I think his first act may be to pay a visit to some rather unfriendly characters who put him in the cage to begin with. With new magic knowledge at hand, thanks to the eagle's willingness to share what he knows, he's also eager to try out some new spells.

Amazing Art by  Nomax