How are Theo and other characters chained to something like the bird in the painting?

Theo and other characters in The Goldfinch are attached to ideas and emotions in much the same say that the bird is chained. The concept of “chained” indicates an involuntary connection. Because the bird is in a painting, it is fixed in its position, but some characters are freed by the novel’s end.
Theo becomes emotionally attached to the idea of his mother’s importance after he loses her in the bombing. More generally, he is attached to the idea of family, which should be a healthy attachment but cannot be in his case, because it encourages him to trust his fundamentally untrustworthy father. Larry, a compulsive liar and swindler, is chained to his pathological personality. Implying that Larry could never free himself, the author symbolically frees him through accidental death. This event also frees Theo from his grasp.
Theo’s addiction to drugs and alcohol is another “chain” that he needs to break. His involvement in a positive effort to restore the stolen goods helps him break that chain.
Theo and Pippa are both tied to the past through their shared experience of surviving the bombing. Theo believes that he could have a future with Pippa, but she understands that this is a projection based on their shared misery, and she rejects it. Her action frees Theo from his mistaken notion.