Over twenty years ago I read a book that I've been searching for ever since. I only remember a few things from it. It had a seashell on the cover. It started with a boy who grew up by the sea, I believe his father was a fisherman.
Later the boy was on his own in a forest where he met a girl, I believe they had sex.
But most clearly I remember them coming to a great big wall inside of which people lived. These people had pets of a sort that they would beat up whenever they felt guilty.
That's all I remember. Takers?