How does the choice of a narrator, persona, or speaker affect the tone of a text?

It depends on the mood of the speak/narrator. If the moon is sad/depressed than the story will have a sad effect. 

As the boys sleep, military airplanes battle fiercely above the island. none of the boys sees the explosions and flashes in the clouds because the twins sam and eric, who were supposed to watch the signal fire, have fallen asleep. during the battle, a parachutist drifts down from the sky onto the island, dead.