ITT: make a bara dude and give him a backstory.
http://atairyu.html.xdomain.jp/charamake/index.html

He was a civilized man at one point, but after being stranded on a magical island in the tropical pacific his body started to grow more manly as he slowly lost his intelligence. Now a bastion of masculinity, he helps the other men who wash ashore on the island, giving them food and shelter. Only able to communicate in small, single words and grunts. He takes care of others as the islands magic grows them into huge, dumb, manly brutes just like him.