Wow. It took me a while to figure out just why this image looks so creepy, but when I did...
See, Remilia is generally handled with two sets of proportions - loli moeblob, and teenager.
However, in this picture, the artist actually used the realistic proportions of a young child (which is, canonically, how Remilia would look). Add a bit more detail and slightly less stylization, and this is probably how Remi would look in real life. A ten-year old girl with wings and pale like a corpse. And that, gentlemen, is creepy as fuck.