I was in the mood to draw today but I’ve been drawing a lot of Vinyl lately, so I asked Pirill out of the blue to name a random female character from the show, and he picked Sunset Shimmer.  
I have a sneaking suspicion he might have a random pony name generator that works kind of like this random number generator, but I promised myself I’d draw whoever he said, so Sunset it was.  
Many thanks to him, Discorded and Mr. Meow for their help and suggestions!
 
I don’t have any kind of backstory for the expression, I just wanted to draw something that I thought looked cute, for no particular reason.  
I didn’t plan to shade it originally but with the colored outlines the mouth basically disappeared in the head fill color so I whipped some shading-like blobs on the image for good measure.