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.
Five main ingredients were used to create this noxious, real-world (ridiculously named), chemical compound, featuring sulfur as the main ingredient. The odor was said to be akin to rotting refuse, decomposing carcasses, and fecal matter. "Who-Me?" Was developed during WW II by the OSS to aid the French Resistance against the Germans. The idea being to utterly humiliate and ultimately demoralize the enemy by making them stink of garbage left to rot under a hot sun.
The bizarre experiment did not last long however as "Who-Me?" could not be administered on select targets (controlled), without making everyone in a certain radius, friend, foe, and sprayer alike, stink as well