emotions

Autistic people may be very unemotional or very emotional.  They may not like changes in their schedule and may react to this with different behaviors including crying, being violent, stemming, etc.  

They may also have problems showing their emotions.  My son jumps up and down and laughs when someone gets hurt or falls.  I believe this is his stemming response to not knowing what to do.  

Those autistic individuals who are "in their own world" so to speak may "seem" to not have any emotions themselves or regarding others.