Well, probably just to make the story interesting.
I am pretty sure that you do not need to change something to make this sentence look better. Gramatically everything is totaly OK, so the last option - that's your answer. As you can see, <span> '[They] used tweezers to pick through innards looking for the heart' the previous tense is being used there, so any pronoun would be possible to use and that also would be proper.
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<span> Characterization occurs through the potentially biased point of view of one character.
The point of view is of one person, telling his story of his time in prison and the people (especially Andy) that he meets. His perspective might be biased because it is coming just from his own thoughts and opinions. </span>
Diluted means watered down or made weaker
