What is the theme in Forged by Fire by Sharon M. Draper?

Sibling Love is another theme. Gerald and Angel don't meet until Gerald is twelve and Angel is in the first grade. Up to that point, Gerald hadn't even known that Angel existed, though it seems likely that Angel, because she lives with Monique, knew of Gerald's existence. On the day they meet for the first time, Monique makes Gerald very angry and he leaves the house. But when he returns, despite being afraid and angry, he's drawn to the little girl. Angel, even at such a young age, is perceptive and realizes that Gerald is afraid