Mesha and Eber are Saphira's personal attending slaves, who've served her since she was an infant. Apparently, they also act as her chaperone and, in all probability, ultimately answer to Saphira's mother Delilah. Not much is known about them because Saphira evidently hasn't been bothered to ask. Having developed an abhorrence for slavery after Abu kidnaps her and adds her to his slave caravan, Saphira sets Mesha and Eber free when she returns to her campsite with her rescuer Branan.
Mesha is described as being a "mild-mannered" bondservant, who performs his tasks "dutifully." Apparently, he is also very discreet in that he is the one who hires the ruffians to accost Saphira at the marketplace in Hebron.
Mesha does not appear to be at all loyal to Saphira, but this may say more about his mistress than it does about him. When Branan rescues Saphira from Abu's slave caravan, and she returns Mesha's scroll of freedom to him, expecting him to express his desire to remain with her, he throws up his arms in joy and cries, "At last!" Mesha's reluctance to stay on with such a wealthy family as Saphira's probably suggests that Saphira can be an extremely difficult employer to please.