During (I believe) the second encounter with the Dark Knight, you get the option to "call friend" which requires a quest. Does anyone know what this quest is or what the scene is about? I haven't been able to find it, but I might just be overlooking something.

Try meeting her when you have Trudy as your companion. To get him travelling with you you need to encounter him four times in total, he usually is hanging around Town of Monsters.