Meet Dark-Sun Guard :3
 
He is the son of Flash Sentry and Sunset Shimmer, and he is also a demon pony (I will explain why lol)
 
This is form one of my alternate Next-Gen universes.  
In this one, Sunset Shimmer and Flash Sentry fall in love and get married. However, because of Sunset’s demon form in the first Equestria Girls movie, in this AU she still has part of the demon form inside her, which affected her DNA (She however, has learned to control the demon form so it can be used for good and is helping her son learn to control his).  
This resulted in her son Dark-Sun Guard being born as part demon/part pony hybrid.
 
Dark-Sun is normally a pretty grumpy and cynical pony, since he was made fun off a lot be kids because of his demon side. He grew up not having very much friends, but the few that he does have, he is very loyal and protective with.  
He might be a grumpy pony and can get angry pretty easily, but he’s a good pony deep down who wants to do good and help others.  
Also loves his parents very much, and so help you if you do anything to try and hurt/offend them.