The idea discussed in both Tim O'Brien's "Ambush" and John Steinbeck's "Symptoms" is the after effects of the combat on the soldiers after a war is over. It talks about what the soldiers go through, their pain and their turmoil once they come back from having faced a war.
Ariel and Caliban are decidedly different in nature and appearance. Ariel as his name proposes is an ethereal and spirit. On the other hand, Caliban is uncultured and un human. The two are associated to the Witch Sycorax who governed the island before Prospero. Hope it helped.
You just hit the biggest lottery of all time! An understatement would be: "I'm kind of excited."
