Ok i just reached the nameless and he just took my options of trying to see what the other replies are but he took my loading ability can anyone fill me in about mr. Nameless and what i should know about him aside from his giant penis?
To see what you can do to try other options you can see previous comments that explain what to do, but If you haven't saved your save and persistent file before choosing, you can't change your choice.
[Spoilers]
For now there aren't many differences. The information I've gathered from other comments are the following. If you don't choose kill him or serve him during the lizard treasure storyline, in the orc's war storyline you can choose to serve him. If you choose to don't serve him, nothing special happens, while if you choose to serve him and after you confirm that you want to serve him or you change your mind once again, you should be able to have a sex scene with him that should be longer and have more scenes based on which enemies love you, that can involve Groth and that can kill you if your sanity is 40 or less. Plus there should be an option of asking to protect Groth linked to a Charisma test.
Like Ben.Dover said, you can change your choice if you have previous 'persistent file' (before you choosing a choice) which automatic generated in your save folder. if you have this one, you just need to replace this file to your save folder in your game folder and in %appdata%>renpy>lustfuldesire... (This one is automatic backup, games which developed by Ren'py usually automatic generated this folder to contain your backup save and persistent files)
Warning: persistent file is a very important file which contain a data of your game play like dialogues you have been read, a choice you have been choose. So it may cause some bug when you replace the old one to the new one.
P.S. This is a method in PC version.
He can also control Korg/Rhot (if no Krog in MC hut) to fight us. And he is the first character that break the 4th wall too. He also the first character who resist our Save-load power too (Othra call it a power to change a fate or something like that). But he can't resist to persistent replacement power btw lol