She was voiced by Isabela Moner in her first villainous role.
She is spoiled,bratty,and selfish. She thinks she’s entitled to whatever she wants just because her father is the mayor. She yells and screams and he’ll just give her whatever. She has no kindness for anyone.
When Gunther shoots her with a dart she just rages at him as they’re being arrested
Heather Muldoon is the daughter of Mayor Muldoon. She was first seen with her dog named "Frankie", before planning to build an amusement park named "Liberty Land" in Liberty Park with her father. Heather was angry because she wanted loads of cotton candy for the entire amusement park. She left Liberty Park by sitting in the long back car.
On the next day, she and her father went back to Liberty Park with Gunther. Heather told Frankie to go get them. Frankie nearly attacked Precious. She pushed him hard. Precious fell in love with Frankie. Heather neared and nearly shot Surly with her slingshot toy. She got 2 dogs were Precious and Frankie. She took them home to her mansion by sitting in the same black car while her dad was driving home. Heather was sitting on the back seat of the car, holding Frankie while her dad did not have time for slow traffic. He drives through cars to bypass traffic to go faster to Heather's mansion. She took Frankie and Precious to the mansion, went to the upper floor by elevator. Heather taught Frankie to do dog tricks. He deserved a treat by doing what she said. Heather taught Precious to do dog tricks, but Precious failed.
Later in Heather's bedroom after sunset, she was playing with her dolls, torturing some of them while her dollhouse had some graffiti. She continued playing with her dolls. Surly and Buddy rescued Precious quietly without getting caught, but Surly accidentally stepped on doll face, so Heather heard the noise. She screamed and chased Precious, Surly, and Buddy and used a slingshot to shoot them, but she missed, no matter how hard she tried. Heather told her father about this loud racket. Mayor Muldoon heard that ruckus, he accidentally fell backward and wore a hippo wall trophy. He was trying to take the trophy off, but it wouldn't come off. Heather tried to shoot Precious, Surly, and Buddy again, but she missed again and chased them. Finally, Mayor Muldoon took off the hippo wall trophy, he almost stopped breathing, he breathes again. He was hit by Precious, Surly, and Buddy. He was accidentally pushed forward by his daughter "Heather". Surly entered Mayor Muldoon's office and punched Mayor Muldoon's bobblehead's head up and it landed on the ground so it shattered into pieces. Mayor Muldoon tried to shoot Surly with a crossbow while Heather smiled evilly, but Surly dodged the shot and the arrow shot 1 cement balcony leg below Buddy. The leg josered into pieces just like smashed shattered glass shards. (joser means "to smash (something) into pieces; shatter"). Buddy fell from the balcony to the ground, looked like he died by falling. Mayor told Surly and Precious to stay out. The mayor quickly slammed two doors closed. (quickly; speedily is called "fastly". Fastly and fast are the same in adverb)
Heather came to Liberty Land with her dad and Frankie. After the grand opening, "Liberty Land" was changed to "Lie Land" thanks to the power problem. They and the others entered the amusement park. The animals were ready to fight. Anyhow, the battle began without a clock. Pigeons chased Heather and Frankie. Heather went into the photo booth and tried to dodge herself, but she was pecked by pigeons. There were snapshots of Heather getting pecked by pigeons. Heather got out of the photo booth, she was mad and angrily screamed at Frankie. Later Gunther was ready to shoot Frankie and Precious by using a tranquilizer dart gun while Heather is smiling like a bad person. Frankie and Precious were dodged from a tranquilizer dart. Frankie thought Precious was shot, but the dart only hit her collar. Gunther was trying to shoot two dogs, but Surly, Andie and Buddy messed Gunther's shot. Heather told Gunther that 2 dogs were getting away. She felt angry, but she found the yellowhammer with its aqua green stripes. (green; yellow mixed with blue is called "skillow") Heather laughed like a vile person and she was chasing Precious and Frankie with the hammer. Heather tried to kill Precious and Frankie using the hammer, but Heather failed, no mattered how hard she tried, she destroyed some wooden boxes. Gunther accidentally shot right in Heather's diaper due to Surly, Andie, and Buddy. Heather was shot by the tranquilizer dart while holding the hammer. She dropped the hammer and it fell and landed on the ground. Andie, Surly and Buddy left Gunther alone. Gunther dropped the dart gun, he was running away while he was sobbing like a baby at the same time. Heather felt weird, walking randomly and she saw Precious and Frankie again. Frankie told Heather to sit and play dead. Heather fell forward on the ground, pretended to die.
First, Mayor Muldoon was arrested so he would go to jail for a long time in the police car. And second, Heather was arrested with Gunther in another police car. Heather's and Gunther's prison sentence wasn't shown. She fought him violently in the police car. Heather would go to a juvenile detention center. Heather was seen one last time for the rest of the film "Nut Job 2: Nutty by Nature" till the ending credits. Liberty Land shall be closed down forevermore without any doubts.
Heather was seen again in the ending credits with her dad and Gunther.
Heather Muldoon's last words: "You... You shot me with a dart!"