This is Lily or Liliam, she is a little OC from the comic “Mama Twilight” https://mamatwilightsparkle.tumblr.com/  
I like that comic series, just a few artists really go that deep in that period of time where Spike and Twilight were young, also i like the way Twilight is like a big Sister/mother for a little guy like Spike, maybe because in my family i saw how that kind of relationship works and i know its wonderfull and all, but with all the grey thigns aswell. Go and check it up, its most worthy