"Broken" builds a portrait of someone out of mismatched pieces. Their brain is scribbled ink, their stomach is full of butterflies, their bones are glass, and their heart is a set of worn gears that never quite started ticking. Almost everything here is delicate, unfinished, or wearing down, and the speaker doesn't hide that.
But the poem turns on its last line. After listing all this damage, the speaker tells the person, "my dear," that this is exactly why they are "strong as iron and mysterious as moonlight." The "soul with the pride of lions" hints at this from the middle of the poem, a sign that something fierce sits beneath the fragility.
The mood is tender and quietly encouraging. The speaker seems to be comforting someone who feels broken, and the message is that being damaged doesn't cancel out strength. It may even be where the strength comes from.