in 1654 charles louis's brother, prince rupert, came to visit heidelberg and soon charlotte realised rupert was in love with marie luise. in order to prevent nocturnal visits, charlotte made luise sleep in her bedroom. trying to protect luise from rupert, she had not realised that her own husband had fallen in love with the same girl. however, one night charlotte woke up and, maintaining that she had found her husband in bed with luise, she attacked the girl, almost biting off her little finger. charles louis protected luise and called in the guard to restrain charlotte. the following day charles louis installed luise in an apartment directly above his own, which was made accessible to him by a secret passage. soon charlotte found out and had to be prevented from ascending the same ladder with a knife in her hand.