A true dork optimist, despite her overt enthusiasm and bubbly personality, Sue tends to find herself under-appreciated and disregarded. Notably she once intentionally disappeared to see if her absence would spark concern; it didn't. She does, however, maintain rather strong relations with both of her parents.
Her relationship with her brother, Axl, is initially strained. Their polar opposite personalities leave them in disagreements and fights more than occasionally, though through listening and understanding one another, their bond strengthens, so much so that they eventually confide in one another about their issues. Sue's relationship with her younger brother, Brick, is much less problematic, as their inability to fit in with the larger crowd causes them to lean on each other for support.
Although she found herself in rather undesirable circumstances on several occasions, Sue consistently maintained a positive outlook on life, refusing to quit after numerous failures. This determination made her a beloved character by fans and viewers alike, and her character concluded in a marriage with long-time crush Sean Donahue.
Brad Bottig: Brad was Sue's first boyfriend. They dated briefly until Sue caught Brad smoking, which led to her ending their romantic relationship. However, Brad and Sue remain best friends.
Matt: In season 3, episode 13, Matt shows Sue a grand gesture to tell her he likes her. This leads to them dating; however, their relationship lasts only a few months before Matt moves to Zionsville. Once there, he meets Sherri, which ends up with him and Sue breaking up. In season 4, episode 15, Matt says he will escort Sue to her Valentine's dance; however, he cancels due to getting back together with his girlfriend.
Darrin McGrew: Sue and Darrin have an on-off relationship spanning over two years (Seasons 4-6). In the episode Valentine's Day IV Sue is left crushed after her ex-boyfriend Matt said he would take her to the Valentine's dance. Darrin is the one to break the news to Sue and offers to take her, so she doesn't have to go alone. They share a kiss while cleaning up after the dance. They begin dating in the following episode Winners and Losers. This stint of their relationship is short-lived as they break up in Dollar Days due to Axl. In the episode Change in the Air, Sue sees Darrin when he comes to the Heck house to fix their air conditioner. Her feelings for him are re-sparked until she finds out he has a new girlfriend. In the episode The Walk, it is prom time for Sue. She is asked by 5 different guys to prom (Sean, Brad, her boss Edwin, Derrick Glossner, and Darrin). She breaks off all her other dates but Darrin because she wants to go to the prom with him. However, when he finds out from Sean that Sue has 5 other dates, he cancels on her, and Sue goes to the prom alone. Darrin eventually goes to Sue after Axl tells him he is mad at him for ditching Sue because Sue really wanted to go to prom with him. Darrin shows up and tells Sue how he really feels about her, and they share a kiss.
Sean Donahue: It starts off with Sean being there to take Sue on prom, and Sue always finds a guy to get out with and rejects him, but when Sean asks her for the Chancellor's Dance, she has to reject him yet again she feels so bad. She spends the dance talking about him. Her date makes her realize that she likes him too much to just give up. On the other hand, Sean also likes She but never had the courage to ask her out, but he liked her too much to just give up. So they both try to get together, but as fate would have it, Sue seems to find herself with other guys, and Sean's every attempt is sabotaged by Brick and Axl unknowingly. In the final episode, Mike makes Sue realize that she shouldn't pine after a guy because she is a ray of sunshine. So as She is about to give up and move on, she Plans to give Sean a parting gift as he is about to leave for Ghana for an internship. As the coincidence would have it, she cannot give it to him face to face, so she slips it in his bag with a sweet note. When Sean is in the airport during security, he finds the gift as it is a snow globe with liquid that isn't allowed. So the check card reads him the note, and Sean runs from there when he realizes it is the same globe he bought for her but threw away after losing hope. He rushes to her and confesses his feelings; in reply, she kisses him, and in the end, they date, break up twice, get back together, and end up marrying.
- Sue has a Twitter account (@SueHeckWins), an Instagram account (@sueheckwins), and a Facebook page.
- 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 the woman approving her name change commented that "Sue Sue" was an interesting, unique name.
- Sue is left-handed.
- Sue had an overbite-crossbite, which was overcorrected to an "unprecedented" overbite-underbite, which resulted in her having to wear headgear at night to correct the issue.
- Sue believes in God.
- She created her own alter-ego - Suki, who, contrary to Sue, is right-handed, parts her hair on one side, and doesn't sweat the small stuff.
- 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.
- Sue had braces for 8 years, from when she was 9 to when she was 17. This is mentioned by Mike in Unbraceable You.
- She got hit on by Tyler, a teen she was babysitting (BabySUEtting), in Get Your Business Done.
- Sue has dated both of Axl's childhood friends, Darrin and Sean, marrying the latter.
- She gets along better with Brick than she does with Axl, stating that she feels the two 'have a special connection'.
- She likes waffles.
- She was born on Leap Day, yet she has had two sixteenth birthdays, as her family floated her 2012 birthday (technically her 4th birthday) to 2013.
- She goes to college at East Indiana State.
- Her phone password is "Sue Heck Wins."
- When she was little, her mom made an arrangement with the nurse's office at school so that she could call Frankie every day at 10:00. She also did not participate in Brownies unless Frankie was the leader.
- The Donahue family taught Sue how to ride a bike.
- Like Brick, Sue has a tell when she lies. Hers is that she often says "and so on and so forth and what have you." after the lie.