Sergeant Amy Santiago is a sergeant and a former detective at the 99th precinct of the NYPD. Always eager to impress, Amy is looking for a mentor to help her achieve her dream of being promoted to captain.
Amy is incredibly competitive. She is always striving to be the best. Amy is intelligent and resourceful in the best of times. Usually while being competitive, she can act jealous toward her partner and later Husband, Jake Peralta, but mainly when they are competing together in Season 1 and 2. Amy is insanely ambitious about making Captain Holt her mentor — or "rabbi"— to the extent that she will become a complete teacher's pet in order to get his admiration. She is very organized and is the butt of many jokes.
Amy comes from a Cuban-American family. She has seven brothers and at least one niece. Her father was a police officer.
As a child, Amy excelled enough in school to skip the 4th grade entirely. She attended a magnet school, where she was voted "most likely to befriend a school administrator." In 8th grade, she was given the key to the teacher's lounge, where she stocked the fridge and cleaned up after the teachers. During high school, she was voted "Most Appropriate." In college, she studied art history.
Amy is highly allergic to dogs, and being near them for more than few minutes could potentially cause an allergic reaction, and she would need medical attention. Her eyesight is very poor, requiring her to wear glasses when she is without her contacts.
Her favorite cop movies, in order, are: Training Day, Lethal Weapon, and Fargo. Amy has one friend named Kylie who frequently set her up on dates before she started dating her now husband. Amy is proven to be a terrible cook, for instance adding baking soda instead of salt to mashed potatoes because they're both white powders. She plays the French Horn and is left-handed.
Amy has long wavy dark brown hair and dark brown eyes. She is usually seen wearing a trouser suit and a blouse or shirt in a black color. She typically pulls her hair back in a ponytail or bun when on the job. In the more recent episodes, she often wears her hair down Amy wears her police badge on her belt.
When she doesn't have her contact lenses on hand, Amy sometimes has to wear comically large glasses.
Jewelry worn by Amy includes: stud earrings, pendant necklaces, a silver watch (on her right wrist), sometimes a ring once belonging to her grandmother, from early Season 5 onwards an engagement ring on her left ring finger. Now starting from the Season 5 Finale a Wedding ring on her left finger.
Read full article on Jake and Amy's Relationship
Though Jake and Amy are partners, they have a very competitive relationship. They often try to one-up each other or participate in bets. Though they often argue and tease each other, it is clear they have mutual respect and share a friendship.
As the series progresses their friendship develops into a romantic interest, a major turning point took place in the episode Johnny and Dora.
In the first episode of season 3 both Jake and Amy state they would like to be more than just colleagues.
As of New Captain, they are officially dating.
As of HalloVeen, they are officially engaged.
As of Jake & Amy, they are officially married.
Read full article on Holt and Amy's Relationship
Amy considers Captain Holt a great leader. She wants him to be her life mentor and often embarrasses herself in her attempts to follow his orders. At one point, she even bowed at him. She was very proud when he corrected her Thanksgiving speech
Rosa and Amy have a very good relationship. In Sal's Pizza, when Rosa tells Amy how she was offered a job as their new police captain in Ropesburg PD, Amy becomes jealous. At the end of the episode, Rosa tells Amy how the two need to have each other's backs. While Jake is in Florida for Witness Protection Program, it is stated that Amy often went to Rosa for support.
Title of Amy's Sextape
Read full article on Title of Amy's Sextape
A reoccurring joke in the show is Jake using double entendres to insult Amy's sex life. The first occurrence was in M.E. Time, though it was during the Halloween episode that Jake first references the titles of her sex tapes.
Read full article on Blaming Amy
Another recurring joke on the show is Jake always trying to push the blame off of himself and onto Amy but it rarely, if ever, works.
Amy embarrassed in front of Holt
Read full article on Amy embarrassed in front of Holt
One of the running gags affiliated with Amy is that she will constantly try too hard to earn the respect of Holt, but by doing so, she will make a fool of herself or do something wrong, which Holt will call her out on. Embarrassed, Amy will back out of the conversation, responding with a forced positive comment on him.
- Amy is allergic to dogs.
- Amy over brushed her teeth, her aggressive brushing technique stripped away much the protective enamel and much of her gum, leaving her with 7 cavities. It is unknown if she still over brushes.
- Amy goes to an adult puzzle camp every summer.
- Amy claims she has made it through 20 years of adulthood without scratching her butt in public.
- Amy is very skilled at reading lips. 
- Amy went to a weekend-long math conference called "Funky Cats and their Feisty Stats".
- Amy is left-handed.
- Amy skipped 4th Grade.
- Amy said she has a cigarette around once a month in her self-evaluation with Captain Holt.
- Amy plays French Horn.
- Amy is a terrible cook.
- Amy is under 35.
- Amy is very claustrophobic.
- Melissa Fumero was pregnant for most of the filming of season 3, giving birth just five days after they wrapped. Therefore Amy's stomach is often hidden for most of the seasons latter half, or in the case of the final three episodes, used as a plot device (Amy pretends to be the pregnant Isabel Cortez).
- Amy is a Wikipedia editor.
- Amy was the president of the Stenographer's Club in high school because she was the only member.
- Amy wrote Holt's mother Wikipedia page.
- She loves Harry Potter and also got Jake into the series.
- Amy officially becomes a Sergeant in NutriBoom.
- Amy's drunkenness scale is shown below:
- One Drink: Spacey Amy
- Two Drinks: Loud Amy
- Three Drinks: "Amy Dance Pants"
- Four Drinks: Pervert Amy
- Five Drinks: Confident Amy
- Six Drinks: Lonely Amy
- Seven Drinks: Unknown
- Eight Drinks: Equestrian Amy
Holt: Something to share with the rest of us, Santiago?
Santiago: No, sir. I- I wasn't... Peralta is the one that was talking!
Peralta: God, you must've been the worst fourth-grader ever.
Santiago: Joke's on you. I skipped fourth grade.
Santiago: Wait, are we going to be graded, or is this just some pass/fail garbage?
Santiago: In high school, I was voted most appropriate.
Peralta: Ooh, self burn! Those are rare.