You can have sex with him during Nameless Plain of Death event. He will invade your mind again and ask if you will change your mind to serve him. If you choose to serve him like there, you can have sex with him as a reward.
I'm not sure that I understand your question right. But if Google translate don't translate it wrong. You can meet Nameless during Lizard's treasure event after you finished Curse of Lust event in Good Ending.
Btw for a question you have been delete. If I understand your question right. You can get Logan 1st heart after you help him in Werewolf event (you need to chase him first). Please make sure you choose to discourage him for going to Bandit camp in Bandit event too.
