These two are actually the same being- they simply switch around with night/day cycles. Unmai is the heifer, Emarru is the mare.
They are locally revered, and are able to see into the future via the mirrors that hover over their heads! Unmai, active during the night, will show a person their greatest moment in her mirror. It is customary to give her a small token of appreciation before she shows you this- whether it be a tasty herb, a beautiful feather, a shiny pebble, a story, a song. Just the gratitude implied with the gift is enough for her! If no gift is given, or if she is attacked, she simply flees.
Emarru is the complete opposite, however. Where Unmai is timid, she is brash. Where Unmai is gentle, she is aggressive. Where Unmai would run, she will savagely beat down any who oppose or insult her. She takes control during the day!
Emarru will show a person the worst moment in their life, and while that may seem like an awful thing, those with enough cunning will begin to plan a way to lessen-or outright avoid- those circumstances, and prevent that seen future from happening. Emarru will only accept the finest pieces of jewelry or fabrics, and any food offerings must be of the choicest meats and fruits. Anyone who tries to offer a sub-par gift will be attacked, eaten, or, if the insult is grave enough, held in place and forced to watch everything awful that will happen in their lives.
Emarru will only release you when she feels you have suffered enough- and someone must suffer an awful lot before her vanity is appeased. The savvy people will turn up just before sunset, so if Emarru does become enraged, it'll be a very short time before Unmai appears and runs off!