Guy on the left is very calm and introspective, takes after his mother in terms of his colours. Meanwhile, the mare on the right is his opposite in how she is extrospective - she thinks about the world around her, rather than about her own inner workings. She is one of the only members of the family to have figured out Princess Coral’s true identity. Her mane and markings are a darker red than most of her siblings.
And the little guy is just kind of a cute, innocent kid. Possibly a little bit dim and easily distracted by shiny things like a predator’s teeth, but nice all the same.