I like how the light spread on Flowey and Frisk. Very nice mix between the many levels of details, like how the sky is different from the sweater, different from the wardrobe, and from the hair. It's pleasant for the eyes. Also the warm and cold colors are well-balanced, many details but not in an exaggerated way. And even if the other characters are not physically present, there is at least a reference of them in every corner of the room.

Good job!