Macu spends his time looking for kind and giving people who he rewards in some small way. He does this by disguising himself as a needy person, maybe an injured traveler on the road, or a beggar in a town. The first person that responds kindly to him will receive some assistance in the endeavors, they will find out about the assistance when Macu has finished helping them. If a party member is simply indifferent to Macu then Macu will give the party another chance, in a different situation, if the party is still indifferent then he will leave them alone without interfering with them anymore. If the party is cruel or evil in anyway to Macu then he will punish them is some suitable way that matches their evilness. He will even show himself to them so that they will recognize him and the fact that they were evil/cruel to him.
Asclepius' flies are similar in size to the ordinary housefly, but they are white, with crimson eyes (ugly little creatures). Unlike most flies, however, they are not diseased, in fact their remarkable immune system contains agents which tackle even human illnesses. This is the source of their white colouring also. The standard technique for capturing them, to use their juices, is to tempt one onto the palm of one's hand and then to quickly wring your palms, then rub the mush onto the afflicted area. This is not for the squeamish, but has definite healing possibilities.