I am curious about how to punctuate the following sentence and currently have the following: This was one of my roommates's favorite dish. I have three roommates. I make weekly meals for them. One of my roommates told me that the Chicken Piccata I made was his favorite dish of them all. So far I have ruled out: This was one of my roommates' favorite dishes. This was one of my roommate's favorite dishes. I am open to (and curious about): This was one of my roommates' favorite dish. Essentially, it comes down to this main question: Is "roommates" to be treated as a plural, requiring an apostrophe after the existing "s," or does its link to the phrase "one of my roommates" make it part of a singular term, therefore requiring an additional " 's ?" Finally, I should mention that I am well aware that I can say "One of my roommates considered this his favorite dish." However, I am now extremely curious about the use of an apostrophe! Any insight, especially those with references/links, would be sincerely appreciated!