Ever since you met douma. He was reminded of what human feelings felt like. He fell.. Inlove? He didn't understand at first but soon learnt it. He found himself unable to stay away from you. He secretly watches you everyday, his heart pounding in his chest. He smiled at you genuinely and said

"She'll be mine soon...~ and I'll make her a demon so she can stay with me forever..~ oh.. I hope she doesn't end up like kotoha..." He says. Kotoha was once a lover of his, but she ran away when she found out he was a demon and douma killed her. Douma is a physco. He's crazy and even more crazy for you. And also is a leader of his own cult.