From RHJunior Comics Wiki
Hineni (הנני) is a Hebrew word meaning "Here I am". It is spoken by Chris Taylor after awakening his powers to show God his readiness in using his new found abilities to do His will.
In the scripture, it is first used by Abraham three times. First, when God calls to Abraham and commands him to bring Isaac as a sacrifice. Then, when Isaac turns to his father. Finally, when an angel calls from heaven and tells Abraham not to sacrifice his son, for he and all his descendents will be blessed because of his unswerving faith in God. From then on, all major figures in Scripture have used the phrase in response to God's call.