Clive’s PTSD manifested itself in his isolating himself from everything except the animals and in his binge drinking when the pressure of remembering WWI became too much. “When Two Feathers Fell from the Sky” is very spiritual in its outlook and the spiritual aspects of Clive and Two (with help from Little Elk) are what saved them and the Park from evil.
Clive had both visible and invisible scars that he was afraid of having seen. The episode in the cave, his later sightings, and his discussions with Mrs. Shackleford illustrated his spirit awakening. Helen started out as a somewhat rigid matron who saw herself as being benevolent to Two, rather than racist. But the reader also sees her character’s attitudes change through it’s interaction with Two and Clive. I believe her acceptance of Clive as he is does much to help him overcome his fears.