@mark1246 There is no reason why he treat her nicely but if I had to guess its because first they are not that close to the point he gets embarassed and she is not bitch enough for him to want to bully her. She treat him with respect and goes with everything he wants so he has no reason to be mean to her.
Does she appear in Rance X? YES! You can put her in your party and she does have events that interacts with some characters sadly she is not that imporant and there is no CGs with her.