Meet the object of Dougan's insane obsession: Genjo Sanzo. Why does Dougan obsess over him? No one really knows. Perhaps it's because he's gorgeous and he just doesn't care?
All we know about Dougan's Sanzo obsession is that Dougan was a former apprentice of Sanzo's when Sanzo took off on his journey west. He left Dougan hanging to run around the desert with three other guys - at least to Dougan's thinking. This annoyed him because he wanted Sanzo to focus all his attentions on HIM. This is where the obsession began and Dougan's adoration of Sanzo took its plunge into insanity.
Dougan discovered all he could about Sanzo's travelling companions and he transformed himself into what he imagined Sanzo's perfect companion to be. He dyed his hair the bright crimson of Gojyo's, he murdered a thousand demons to become a demon himself - just like Cho Hakkai. He gained the awesome power of Son Goku, and when he was ready, he went out after his prize: the esteemed Sanzo Houshi.