Micah's such a good kid, we feel for him when bad stuff happens to his family. He runs a long distance from the family farm to the town of Ferne to get a magician to help his mom with a difficult birth—and then the magician robs them and lets his mom die.
Before that happens, Micah is full of hope: "His feet felt light, dancey, silly" (3.43). He is really into the idea of being a big brother, too: "Micah straightened his shoulders. He was ten years older than tiny Sadima. He would protect her" (3.45)—and even with the awful death of his mother, that's exactly what Micah does. He picks up newborn Sadima, carries her into the barn, and curls his body around hers to keep her warm in the hay all night.
Micah really does seem to have a special bond with his sister, and we kind of wonder if it's an early manifestation of her magical abilities. Like when she whimpers as a baby, "Micah jerked in response" (3.56), and whenever she cries, "Her sobs tore at Micah's heart" (5.11). He kills a rat that is climbing on her because he's afraid that it might hurt her, "and rat bites often got infected and left scars" (5.20). Of course, Micah had no way of knowing that Sadima was perfectly safe, since she has an empathy-thing with animals going on.
It's nice that Micah tries to protect her and all, but ultimately he doesn't understand her. When Sadima explains about meeting Franklin and the bond she'd felt with him, Micah tells her: "I am just glad Papa died… His heart was broken the day you were born. This would have gutted him" (13.21). Maybe Micah's more like his father than he would like to admit. He storms out, and Sadima leaves without either of them making up. There went that nice brother-sister relationship.