These days he wears a helmet instead of a crown, but that doesn't make him any less of a king.
He is still a grown man trapped in a child's body, a great lord without a throne, but this time around – after his second (and final) return from Narnia – he isn't angry, but driven. There's a calmness to him now: a certainty that wasn't there before, and even his siblings are astonished by the change. Sixteen he may be, barely on the cusp of manhood by ordinary standards, but there is such strength and determination reflected in the depths of those baby-blues that even his mother cannot help but bend to his will, no matter her reluctance. He will have his way and accept no alternatives.
Of them all, it is Edmund that understands his decision best, and his letters are always quick to assure Peter that he has everything taken care of on the home front and that he mustn't worry about them, but about his mission – and he never expresses any doubt regarding just what Peter is searching for, in the filth-infested trenches and in the blood-soaked cities of war-torn Europe, though Peter himself sometimes questions his own motives. Sometimes he fears all his efforts are useless.
The evils he once faced as king pale in comparison to the horrors he has witnessed as an English soldier, and his dreams are no longer as sweet and hopeful as they once were. Still, he refuses to give in to despair. The other soldiers look to him, despite his age, and tears are a weakness he cannot afford. He will fight, and as he slips into a fitful sleep each night he will cling to his lost innocence and one last, undying hope, a whispered prayer: “Caspian.”