The sun is high in the sky; tranquility flares. -> Could be reference to Solstice, his mother.
Mood shifts, light to dark, dark to light. -> Colour reference, tobiano
Peace becomes war, war becomes peace. -> He participated in the invasion
Which is more important to you, little lamb? -> Reference to his sister and mother
A coward until you know what you've lost. -> His mother has been stolen.
But the lost one depends on you, -> His mother is stolen
And you will use all that you were taught. -> He has mentors, who teach him how to be stronger