| “ | We're an amazing team. We're the sleuth sisters. | ” |
―Rosa Diaz in "White Whale" | ||
Rosa and Amy are friends and colleagues. Amy is the first person to visit Rosa's apartment but this causes Rosa to move the day after. Though both are female Latinas and presumably best friends, their personalities also differ, with Rosa tending to be tough and intimidating and Amy tending to be more nerdy and good-natured.
Season One[]
In Sal's Pizza, Rosa says to Amy that she has her back, and that they should have each other's backs in a precinct full of dudes. Amy concludes that they had a moment.
Season Two[]
In Windbreaker City, Rosa and Amy make a bet to see who can score the most kills in the training simulation as a way of deciding who gets the next Saturday off from work - Rosa claims she wants the day off to go to dinner with her family, which Amy doesn't believe.
Season Three[]
In The Oolong Slayer when Amy made The Vulture perform with his band at his own birthday party, Rosa called her an evil genius and Amy replied by saying it's the nicest thing Rosa has ever said to her.
Season Four[]
In Halloween IV Amy chooses Rosa as her Team player for the Halloween Heist. Rosa tells Amy: "You're such a Mary Anne." to which Amy replies: "I am, it's true."
In Monster in the Closet, Rosa picks Amy as one of three maids of honor for her wedding to Adrian Pimento. Jake and Amy realize that Pimento and Rosa don't want to get married and confront them. Rosa thanks Amy for planning her "not-wedding wedding" in her speech.
In Skyfire Cycle, Amy and Rosa discuss a fight between Holt and Kevin. Amy refers to Holt and Kevin as "our [Amy and Rosa's] dads", implying that she sees Rosa as her sister. Rosa teases Amy by mentioning how "your [Amy's] dads had sex" afterwards.
Season Five[]
In, Gray Star Mutual, Amy is looking for a dress for the wedding, and Rosa knows she is keeping it secret. Rosa tells Amy it's alright for her to find a beautiful dress even though Amy finds that in her new position it's difficult to get the respect she deserves. Rosa helps Amy to find a dress, and they take down a suspect.
In Show Me Going, after the active shooter situation, Rosa allows Amy to hug her, despite her being covered in toilet water. The water came from the toilet Amy was attempting to fix for Rosa.
In White Whale, Amy and Rosa chase a criminal who escaped from them seven years prior. After he escapes, Amy tells Rosa that she found her intimidating when she first joined the 99, and therefore chose not to tell her about how she accidentally let him escape. Rosa tells Amy about her past (medical school, business school, and having a pilot's licence), which shocks Amy. They also take up the name "the Sleuth Sisters" and are shown to have an elaborate handshake.
Season Six[]
In He Said, She Said, Amy investigates a sexual assault case, and tells the victim to press charges, despite Rosa's objections. In the end, Rosa tells her she was right, as it inspired other women to speak up.
Season Seven[]
In Manhunter, Amy comes to Rosa for help when she thinks she might be pregnant. Rosa helps her throughout the entire day and even gets her a pregnancy test.
In Ransom, Rosa competes for Amy in a competition to win an expensive stroller. It turns out Rosa had already bought her and Jake a stroller.
In Lights Out, Rosa tracks Amy's contractions when she goes into labour, in order to convince her to go to the hospital. Later on, Rosa helps a firefighter deliver Amy's baby despite being uncomfortable with it.