Two kinds of dual possession — with two names, and with a name and a pronoun — are stumbling blocks for even the smartest writers. Is it Elaine’s and I’s coffee pot? Jill’s and Jack’s pail of water? The rules are specific; you just need to follow them.
- Our dog pounced on Avery’s and Morgan’s cat with significant consequences.
- They came to look at Peter’s and she’s car but bought another one instead.
- Karen’s and mine’s stealthy correspondence lasted many years.
When two people own something together — call them Avery and Morgan — then what they own is Avery and Morgan’s property, with the apostrophe at the end of the second name of the unit of Avery and Morgan. If it’s Avery’s and his property (using a pronoun), the apostrophe is placed at the end of the first name of the unit of Avery and him; the possessive is already there in the pronoun his.
Does the sentence have two names? The apostrophe goes on the second name: Jan and Robert’s pizza. Does the sentence have a name plus a pronoun? An apostrophe belongs on the name only: Jan’s and my pizza. Never use an apostrophe with a possessive pronoun (“my’s”).