Answer:
This comparison creates the image of a completely helpless victim.
Step-by-step explanation:
The author of the sentence shown in the question above used a metaphor to compare Lyra to a fly that was tied to a spider's web. The spider is a predator of the fly, which once trapped in the spider's web, cannot escape, becoming a completely defenseless prey that cannot be released.
In this case, the metaphor shows Lyra's weakness in relation to her captors, which she has no chance of escaping.