These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Under The Northern Lights
Alternate Character Interpretation: In-universe. The reindeer have very different views from ponies (and viewers/readers) on the main six. The reindeer believe the Main Six are Celestia's personal wetworks squad, a team of hand-picked elite troubleshooters led by "the most powerful and evil sorceress in the world", who take care of all major unrest in Equestria, and let Celestia be the benevolent ruler of a perfect little sugar bowl as far as everyone else is concerned.
Uncanny Valley: Invoked within the story. Spike finds nidhoggs disgusting because they look very similar to dragons but clearly aren't dragons.