Let my beard comfort you
Gaster signing with his actual hands for a change of pace, haha.
Edit - Check out Jamadubs' dub! (Spanish)
I remember hearing that children who grow up in un-loving families or traumatizing situations sometimes don't develop empathy or understand love, as they have never experienced it. that or Gaster is just like this naturally.
Good or bad, I have a deep interest in characters that don't experience empathy. the good ones are even more interesting though, as they try to do good but don't have any natural indication of what "good" is, And need some other method of figuring it out.