Who is caspar Grattan in the moonlit road?

He is the narrator of the second part of the story...... note- he is the same narrator from the first part, but he has no memory of his youth and has therefore renamed himself....... Caspar Grattan.

"In the second part of the story, "Statement of Caspar Grattan," the narrator has been delivered into the world as an adult, but without any memory of an earlier life. His began twenty years ago, at the moment of his emergence out of the forest. He has given himself the name he now bears. Grattan describes a life of guilt-ridden wandering as a kind of social and psychological outcast. When he tries to name the source of the guilt, he can only offer a dream that sounds like the life that Joel and Julia Hetman (although Grattan never mentions their names) might have lived. He describes an attempt to test his wife's sexual fidelity "in a vulgar, commonplace way familiar to everyone who has acquaintanceship with the literature of fact and fiction." [4] He returns from a visit to the city and discovers (or believes that he has discovered) a man leaving his house. Grattan then finds his wife cowering in the corner of her room, and murders her in a fit of jealous rage. A second dream involves his dead wife confronting him on a moonlit road at night. He concludes his "Statement" with an ironic reversal of an expected trope:

My penance, constant in degree, is mutable in kind: one of its variants is tranquillity. After all, it is only a life-sentence. "To Hell for life"—that is a foolish penalty: the culprit chooses the duration of his punishment. To-day my term expires.

To each and all, the peace that was not mine. [5]

Suicide appears to be his intention, but whether or not his "term" will expire, is a question that remains open at the end of the story."