"Zi is not a good person" means "You are not the right person", and "Zi" means "You". Ancient couples called each other lovers. In ancient poetry, "lover" is often used by wives to address their husbands.
"What's there to be afraid of?" means "I'm afraid of." "Dust fiber" refers to tiny things, which refer to everything and are in harmony with the above-mentioned "everything".
It is said that "loving someone is like having a soft rib and armor", and so is this sentence. Forgive everything in your heart to tolerate everything. If you are not my lover, then you are not my armor, let alone my weakness. Then what do I care about you? What am I afraid of?