Charles has at least one sibling, a sister, but she isn't seen at his father's wedding. His grandmother bought him and his sister a Princess Tower, which he played with when he was younger.
When a criminal attempted to shoot Diaz, Boyle leapt in front of her and was shot twice in the butt. She believed that he saved her life. For his act of bravery, he was awarded a medal of valor.
Towards the end of season one, Boyle gets engaged to Vivian Ludley, a woman who works with Kevin Cozner, but they never got married because she wanted to move to Canada.
Every year, Charles dresses up for Halloween, and every year, no-one understands what his costume is.
Charles used to be madly in love with Detective Rosa Diaz, with whom he stood no chance at all. Charles has since moved on with Vivian Ludley and is currently in a relationship with Genevieve Mirren-Carter, with whom he has an adoptive son, Nikolaj Boyle.
Charles is mild-mannered, eccentric and optimistic. He is also an intensely critical foodie, but is also needlessly critical of almost everything around him.
He has an extremely close, almost brotherly relationship with Jake Peralta - who acts primarily as Charles's guide. Charles worships Jake to the extent that he becomes violently jealous at the concept of being replaced. He also involves himself unnecessarily deeply with Jake's relationship with Amy, which both parties see as creepy and annoying. In spite of this, Charles cares a great deal about his friends
His critical-as-hell nature leads him to completely unnecessary acts: when photographing a criminal, Charles worries hysterically about how the lighting of his position doesn't contribute to the man's complexion on the photo.
He is also incredibly dramatic - when Jake comments on how he read a certain book, he violently snapped Quit calling it a book. It was a visual journey!. He also commented at one point his belief that the god of rhythm was Sebastian from The Little Mermaids.
In spite of his eccentricities, Charles has frequently shown himself to be extremely brave when he needs to be - he throws himself in the path of an armed criminal when he realises that Rosa was about to be shot by that criminal, only to end up getting shot himself.
Terry describes him to be one of the most hard-working detectives in the precinct, despite not being the most brilliant of them.
Charles is very clumsy and is one of Jake's best friends. Though at time Charles can be ridiculous, the two look out for each other such as when Jake helps Charles when he goes "Full Boyle".
Charles often gets jealous whenever Jake seems to develop new friendships. It is evident in "Undercover", "The Cruise", and "The 9-8". He is also incredibly loyal as Jake mentions in "Yippie Kayak". This trait of his is evidence in multiple episodes, throughout the series.
Charles used to have a large crush on Rosa up until meeting Vivian. After which Rosa and Charles started to have a close friendship.
Charles was the first character Rosa told that she was Bisexual and in a relationship with a woman.
Charles and Gina started sleeping together occasionally as of the end of season one although it is only casual and the two eventually end their friends with benefits relationship. They then decide to work together to break up their parents after they start dating.
Charles and Terry seem to have a close relationship. They are shown to be friendly when Jake takes them both to Puddlelake manor and help each other through it.
Charles and Holt have a friendly, professional relationship. Charles is shown to be loyal to Holt, as he sometimes feels conflicted when both Jake and Holt ask him to do different things. Charles is shown to want to bond with Holt and he is happy when Holt is revealed to be a natural chef.
Charles and Genevieve are a couple and share a lot of strange habits and quirks in common with one another, which others often find repulsive. They decide to have a child together and have adopted Nikolaj despite only having been together for a few months.
Charles and Vivian were previously engaged however they broke up over disagreements on moving to Canada. They met in the episode "The Party" and were both shown to be foodies. Vivian is very impressed by Charles's culinary knowledge and the two end up making out in the closet. Vivian, like Charles, is shown to go 'Full Boyle'.
- Charles is a major food lover and critic.
- Charles’ best friend is Jake Peralta.
- His favorite cop movie is "Turner and Hooch".
- He had a crush on the teapot from "Beauty and the Beast".
- Charles went to Sarah Lawrence College.
- Charles was born in Staten Island, NY as seen on his marriage certificate.
- He played Pocahontas in his third-grade play because all the girls were too big.
- The academy invented a new weight class for him and is the undisputed bubbleweight champion.
- Charles is right-handed.
- Charles has always been a huge supporter of Jake and Amy’s relationship. Even from the beginning. During Jake and Amy’s first meeting in 2009, Charles says he “hears wedding bells”.
- Every Summer, he and his father take a road trip across the country using an RV.
- Charles was the first in the Nine-Nine to find out that Rosa was Bisexual ("99").
- In Maximum Security, Charles states that he is unsure as to whether or not he believes in God, which implies that Charles might be Agnostic.
- In the episode Christmas, Charles states that he has gone 42 years without getting a lump of coal. This means he is at least 42 years old.
- Peralta: Did Nancy Drew solve a lot of murders?
- Boyle: Yeah, she did. Murder on Ice. Recipe for Murder. Nancy was a wonderful detective. I wanted to be her when I grew up.