Depending on the sentence, a pronoun should be placed before or after the verb. In a statement, it will be before, such as in "I can buy a necklace." In a question, it will be after, such as in "Can I buy a necklace?" (which is after the helping verb but before the acting verb)
Answer:
sadness or misery
Explanation:
he's trying to convince whomever that letting him become his assistant will bring together something that can only bring good things. Like turning sadness and misery in their home to pure love
Your answer should be WHO.
Think of it like this: You wouldn't say "The boy it (a variant of 'which')", because it simply just sounds odd. Instead, you're wired to think "The boy, he (an unknown name, so it would be 'who')".