My mother buys a new rice cooker.
If I'm correct in thinking the play is "Romeo and Juliet", then Mercutio is related by being a character in said play. Hope this helps.
The pronoun that complete the elliptical cause is "I" because sentence uses the word "My" in the very beginning of the sentence so that person is either talking for themselves or someone else, if for someone else than a name would be in The list of answers.
