The speaker is an older sibling or carer, addressing a much younger child who has become their reason to keep going. The poem moves through three memories: the child's calming gaze, a moment of comfort when both seem surrounded by pain ("landmines of broken glass"), and a scare at a pool when the speaker looks away and the baby falls in. The rescue ends happily, but the speaker still feels they broke a promise.
The last stanza jumps to the present. The child is older now, insisting she's "old enough to know," while the speaker stares blankly and traces a doll's shoulder. The poem suggests the speaker is carrying something heavy, and the child's innocence makes it hurt more. So they put on a smile.
The mood is tender but anxious. Love and guilt sit side by side, and the quiet ending shows how much the speaker hides to protect someone else.