So these are the canon characters you can choose from. I will update the chapter when they begin to get taken.

Frisk: Taken
Toriel:
Asriel:taken
Asgore:
Sans: Taken
Papyrus: taken
Mettaton: Me!
Alphys:
Undyne:
Gaster: taken
If I missed any then just tell me.

We will not start until we have at least frisk, sans and papyrus
You also need to put the password hidden in the first chapter.