Jim Paxton, a policeman in the San Francisco Police Department, met and became engaged to Maggie Lang, who had a daughter Cassie from her previous marriage to Scott Lang. Paxton disapproved of Scott due to his criminal background, and Scott in return thought of Paxton as an "ass-hat". Although Cassie preferred her father, she seemed to like her soon-to-be-stepfather, and Paxton was never anything but kind and protective towards her.
Cassie's Birthday Party
Scott Lang arrived at Cassie's seventh birthday party after being released from San Quentin State Prison. Paxton quickly confronted him and made it clear that he was not welcome as Lang had failed to pay child-support. They continued to argue while Lang gave his daughter her birthday present. Eventually, Maggie arrived and intervened, taking Lang outside to discuss what he needed to do to see his daughter after he had accused Paxton of being an "ass-hat". Paxton stood with Cassie as Lang left the party and drove away.
Arresting Scott Lang
A few days after the birthday party, Scott Lang was arrested for breaking into the home of billionaire Hank Pym, although he claimed to have not been caught stealing anything, but instead returning something he had stolen. While he waited in his prison cell, Paxton approached Lang and told him how disappointed his ex-wife and daughter would be to learn that Lang had returned to his criminal ways. Before their conversation could continue, Lang was called to a meeting with his lawyer.
A few minutes later, Paxton was warned by Gale that Scott Lang had seemingly vanished from his cell and escaped. Furious to have lost him and determined not to allow Lang to escape, Paxton ordered his men to set up a five-block perimeter and find Lang. In the end, they failed to find him; Paxton became obsessed with finding Lang again.
While having dinner with Maggie and Cassie Lang, Paxton received a text message from Gale which informed him that the man posing as Scott Lang's lawyer before the breakout was billionaire Hank Pym. As Paxton left to investigate the case further, he was asked by Cassie if he was going to find and arrest her father, which Paxton assured them both that he would, though he made it clear to her that all he wanted was for him to be safe. Cassie told Paxton she hoped he did not find him.
- "All the chaos in here! Multiple shots fired... and there’s a tank."
- ―Jim Paxton
Paxton and his partner Gale arrived at Pym Technologies where they confronted and attempted to arrest Hank Pym; however, Pym insisted that he had to get inside as he had lives to save. Although Paxton continued to insist that Pym had to come with them, they were suddenly distracted when they noticed that Dave was stealing their police car. The pair left Pym and gave chase to try and save their car.
They found their car down the road having been crashed into a tree. As they made their way back to Pym Technologies they overheard a strange horn tune playing from a nearby van where Dave and Kurt were hiding, which Paxton remembered as Scott Lang's horn. Paxton and Gale walked over to the van and insisted that the pair of criminals get out, although they tried to pretend they were not there. Paxton and Gale pulled the doors open and pulled them out, but not before Kurt managed to press a button on his laptop.
As Paxton and Gale handcuffed Dave and Kurt, they witnessed all the inhabitants of Pym Technologies charge out of the doors, screaming in fear. Paxton attempted to control the situation and work out what was happening, but without warning, a tank burst through the building's walls and landed by the entrance, leaving Paxton unable to explain what was happening. Paxton witnessed Hank Pym and Hope van Dyne climbing out of the tank and taking Pym for medical treatment due to a bullet wound in his shoulder.
Paxton followed reports of a helicopter crash and a fight between two super-powered individuals in a family's home. When Paxton and Gale arrived, he found Scott Lang in a strange uniform, having just defeated Yellowjacket and saved the family. Although Lang tried to explain what was happening and make the confused Paxton understand the situation, Paxton ignored him and instead pulled out his taser and shocked Lang, knocking him out and putting him into the police car to be taken back to jail.
As they drove along back to the police station, Lang woke up and insisted that Paxton needed to let him go as something very dangerous was about to happen. However, Paxton angrily spun around in his seat and threatened Lang, ordering him to keep quiet. As they were driving, a call came through the radio that a situation had occurred at Paxton's home and Yellowjacket had taken the family hostage. Paxton turned the car around to drive there while Lang suddenly disappeared from the back on the car.
Protecting the Langs
As Paxton arrived at Maggie Lang's House, he was informed that his step-daughter Cassie Lang was taken hostage by Yellowjacket. However, Ant-Man interfered and the two had fought in Cassie's room. Paxton attempted to come and rescue her, but was trampled by an oncoming Ant that had been enlarged with a Pym Particle Disk.However, Paxton recovered and protected her while being threatened by Yellowjacket, who was determined to kill the Lang family simply to torment his foe. Paxton watched as Ant-Man went subatomic into the Quantum Realm and killed Yellowjacket by causing his suit to malfunction and shirk with him still inside. After Ant-Man had enlarged back to normal size, Paxton was reunited with his wife and daughter together, despite some wreckage of the house sustained by an enlarged Thomas the Tank Engine toy.
In gratitude for saving his family from Darren Cross, Paxton invited Lang for a family dinner and informed him that he would not be going back to prison after escaping the last time.
In 2018, Paxton and Maggie arrived at Scott Lang's House to pick up Cassie only to find Agent Jimmy Woo and the FBI searching the place. Maggie tried protesting but Paxton reasoned that the FBI were merely doing their jobs.
As they were leaving, Paxton and Maggie give Lang a group hug. Paxton then gave him an extra hug. As Lang bade them goodbye with magic trick involving cards coming out of his mouth. A confused Paxton wondered aloud how Lang pulled that trick off.
The next night, Cassie video calls Lang to ask for her missing soccer shoes for her upcoming game. When Lang answered, he claimed he was too sick to search the house, so Paxton, Maggie and Cassie wish him luck with recovering before signing off. Paxton accompanied Maggie and Cassie to Lang's house to pick up Cassie's soccer shoes only to find it a complete mess with bite marks on a nearby fern. Then suddenly, Woo and the FBI burst into the house, believing that Lang violated his house arrest. Cassie soon blocked Woo from searching the bathroom, insisting that her father was extremely sick, but Woo forced his way past Cassie. Paxton and Maggie try to stop him only to be barred by Agents Burleigh and Pearson.
As the FBI re-check Lang's ankle monitor, Maggie accused them of harassment, but Paxton told her it wasn't. Pearson then entered the room to announce they that had arrested Hank Pym and Hope van Dyne. Woo then left, promising to return for the official end of Lang's sentence.
Later that day, back at Maggie's house, Paxton shared confused looks with Maggie as they view Giant-Man on the news.
After Lang was officially paroled, he came to Maggie's house, where Paxton and the entire family gave him a celebratory group hug.
Jim Paxton appeared to be a step-father who truly loved his step-daughter, Cassie Lang. But he hated her father, and his rival, Scott Lang very much. He always wanted to arrest him due to his criminal background as a thief, thinking relapsing would be too tempting. Scott has described him as being an "asshat" for his hardheaded personality. But Paxton can easily feel grateful when someone saved his step-daughter like Ant-Man saving Cassie from Yellowjacket. So that was what made him becoming thankful to Scott. After that skirmish, Jim is now on good terms with Scott, now understanding that his heart is in the right place. Later on, Paxton is now good friends with Scott, to the point he even hugs him when picking up Cassie.
To be added
- Glock 26: Paxton and other officers of the San Francisco Police Department carried a Glock 26 as their service weapon. Paxton drew his gun to apprehend the wearer of the Ant-Man Suit, believing him responsible for the destruction of Pym Technologies Headquarters. When this man revealed himself to be Scott Lang, Paxton resorted to use a Taser instead. He also tried to use it to rescue Cassie Lang from Yellowjacket, but he was quickly disarmed.
- X26 Taser: Paxton used this weapon to subdue Scott Lang, once he managed to chase him while he believed Lang was responsible for the destruction of Pym Technologies Headquarters.
- Maggie Lang's House: To be added
- In the comics, Scott Lang's ex-wife remarries a man named Blake Burdick, who was distrustful towards Lang.
Behind the Scenes
- Patrick Wilson was casted as Jim Paxton, but after the movie was delayed, scheduling conflicts forced Wilson to drop out and Bobby Cannavale took the role.
- Tim Soergel was a stunt double for Bobby Cannavale in the role of Jim Paxton.
- Jared Leland Gore was a stand-in for Bobby Cannavale in the role of Jim Paxton.