I wish I could know how to meet him
As you progress through the story quests you'll eventually start the "Lizard's Treasure" quest. You can view it through ur quest log, the scroll button next to equipment. Towards the later end of the quest you'll start getting nightmares some of which you need to sleep at your house to see. Just sleep and you'll meet him in the nightmares. How you react to him will determine what accessory he gives you as well