Sue Sue Heck (born February 29, 1996) is the dorky, socially awkward, late-teen middle daughter of Frankie and Mike. Although she may be socially awkward, she appears to have more success socially than her younger brother Brick. She is dorky, overemotional, and wirey and stays usually positive. She seems to fail at everything she tries out for, but her optimism and determination keep her trying again and again. She wears braces on her teeth. Her first and middle names are "Sue", as it was mistakenly written down twice on her birth certificate. She is usually in a cheery mood even though she is often put down by athletic older brother, Axl Heck. A running joke throughout the series is that nobody notices her or remembers her name, except for Reverend Tim Tom, whom she greatly admires. She is a huge fan of Justin Bieber and One Direction. Her birthday is February 29th, so she only gets to celebrate her "real birthday" once every four years and therefore becomes very excited about Leap Years. When she was in eight grade she managed to get on the cross country team due to it being "no-cut". For the rest of the school year she wore her team sweatshirt everywhere, which caused her to faint in one episode because of the heat. Cross country was later cut by the school board. Upon starting high school she was briefly a part of the cheerleading squad due to a mix up in phone calls. The Wrestlerettes are Orson High's cheerleaders for the wrestlers created by Sue Heck . The 4 original members are dorky Sue Heck, estranged Ruth , tough mean Becky , and Weird Ashley the wizard wannabe. There is a 5th additional member, Brad. The Wrestlerettes competed in a cheeroff against the cheerleaders presented an amazing eccentric performance featuring the 80's song "Fame" by Irene Cara. This is where Brad shows up close to the end. They ended up winning.There are currently three other girls on the team, all of them being even more socially inept than Sue is. Her closest friend is Carly who she is mostly seen with. She is about the same on the school popularity scale, although one time Carly took off her glasses and braces and became more popular, especially with boys. Sue's other best friend and first boyfriend was gay Brad, but after she found him smoking, they broke up. Sue started to date Matt in The Map, but they broke up in The Paper Route due to him moving away. She dated Axl's friend, Darrin, but they broke up. But, they both still have some feelings for each other which was proved in Season 5. It seems that they will get back together since Darrin broke up with his girlfriend, and they both are obviously stil in love with each other. Also, they kissed in the episode 'The Walk' and got back together.
Sue is usually forgotten by Mike. When watching a drive-in movie, Axl Heck claimed every parent has a favorite child; their mother Frankie Heck denied it, but Mike implied it was true. Mike claimed he and Axl have a lot in common, such as football and other sports. Sue was upset. Sue took out a scrapbook and labeled it The Summer of Sue and Dad, and alerted her father about the project. Mike then started giving Axl negative attention and Sue none at all. Going to a fair, Axl had his school paper in his truck when he wreck it and got towed. Frankie got upset and no one would listen to poor Sue. At the fair, Sue went to the lost and found for children wanting her family to wish to find her. After a while, the family came there to ask if they'd found the paper and left without Sue. At night, watching the fireworks, Axl stated he liked Mike better then Frankie. Sue got all worked up about how mom does everything for them. Younger brother, Brick Heck, then lesser stated he liked dad better. Sue slipped out accidently she liked dad better. They all agreed to forget about it and have no favorites. Back at the house, Sue completed the scrapbook with fun pictures and Sue called it The Summer of Sue and Dad. For the longest time, Mike didn't know the potato place Sue worked at in the mall or what her JPLA meant. Mike kept trying to ask people to go with him to the basketball game and later took her out to lunch asking her what JPLA meant and agreed to attend one. When somebody denied, Sue agreed to go but Mike ignored her. It then showed flashbacks of Sue asking to go places and she didn't get to. Frankie got angry that Mike wouldn't take Sue because she's a girl. Mike ended up taking Sue even when somebody else agreed also. Mike does go to a lot of Sue's sport tryouts even though she's terrible.
In The Bee , Mike was proud that Brick was in a spelling bee and won in his school. Mike continued to coach him. Both Mike and Frankie have forgotten Sue's birthday and took her to Chicago next weekend which Brick's championship was taking place. Frankie promised Sue could pick the hotel, restaurants, etc. on her "birthday trip".
In season 5, they meet again while Darrin is fixing the air conditioning when Sue Heck is taking out the trash. Darrin meets Sue over a garbage can where they meet and are still friendly. Darrin had movedon to a hairdresser with an Italian New York City accent and hairdo named Angel. Sue met Darrin and Angel in the front yard and Darrin told her that they were going to see a movie. Sue thought she was invited. Sue decided to spend a day with Angel and get her hair done. Sue asked Angel what she liked about Darrin. Angel liked his arms and face and obviously only liked him for his looks. Sue discussed this with Brad. And Brad said he supported Sue's decision but was really against breaking up with him.
When he said just the two of us she thought he meant without Angel. She came to her senses and realized that it was over. Darrin saved Sue in The 100th, when Sue was about to be hit by the cow float that was on fire. In Sleepless in Orson, Darrin saw Sue kissing a troubled teenage neighbor, Derrick Glossner, and it seemed as he wanted to get her back, because he was holding a teddy bear and flowers.
As of now, Darrin still has feelings for Sue. And it seems that they may get together at some point since he has broken up with Angel.
In the episode 'The Walk' several guys asked Sue to go to prom with her including: Edwin (her boss), Brad, Darrin, Derrick Glostner, and Sean. Sue didn't go with Brad because she only really wants to go with Darrin. Sue called it off with the others. Once Darrin heard that Sean had been rejected because Sue had to many pro dates, Darrin left a message on Sue's phone telling her that he's not taking her to prom. Sue was very upset. Sue went to prom alone meeting up with "Weird Ashley " who Axl accidently went to prom with twice. Darrin showed up at the prom and kissed Sue meaning that they're most likely back together.
- Sue is left-handed. 
- Her favorite color is pink.
- Her full name is Sue Sue Heck due to an error made by her parents on her birth certificate. She almost changed her middle name to Lily once, but she changed her mind at the last minute after someone commented that "Sue Sue" was an interesting, unique name.
- Sue had an overbite crossbite, which was overcorrected to an "unprecedented" overbite underbite.
- She loves peach scent.
- Sue believes in God.
- She often fights with her brother Axl.
- She created her own alter-ego - Suki, who, contrary to Sue, is right-handed and parts her hair on one side.
- She called herself a Frosh when she started High School.
- She almost once tattled on Axl for sneaking in after curfew, but he fessed up and she didn't, she got rewarded by Mike and punished by Frankie for this.
- She is getting a palate expander.
- She got hit on by Tyler, a teen she was baby sitting (BabySUEtting).
- Sue has had three boyfriends so far: Brad, Darrin, and Matt.
- She once tried out for cheerleading and, to her surprise, received a phone call informing her she made the team....only to find out the next day that the phone call had been a mistake.
- She had to wear head gear.
- She gets along better with Brick than she does with Axl.
- She can be very naive and gulliable.
- She likes waffles.
- She was born in a leap year  yet has had two sixteenth birthdays.
- She still loves Darrin, and he loves her.
- She goes to college at East Indiana State.