Second, Her tail has a devil point to it.

Third, Papyrus and Sans are her step brothers (Same dad, different mother.)

Fourth, she is 16, and has a high pitch voice, and is 4 foot 6, so she is mistaken for an 11 year old.

Fifth, she likes Geno (AfterTale Sans)

And finally, sixth, she cuts herself and has an abusive, attention seeking sister (the sister's name is Bethany.)