There's a lot that goes into the construction of a character to make them believable so the viewer can take their journey alongside them, which includes every line of dialogue, no matter how important or seemingly meaningless those lines are to the movie in question.
Ant-Man was Peyton Reed's 2015 entry in the Marvel Cinematic Universe that surprised fans with a comedic heist and a large cast of characters that grew over the course of the film, which can be explored further by examining each of their first and last lines and how they relate to their development throughout the film.
Hank Pym
First: "Stark!"
The film opens in the past at S.H.I.E.L.D.'s Triskelion headquarters as Hank Pym interrupts a meeting between Howard Stark, Peggy Carter, and Mitchell Carson. Pym was outraged to discover that his research was being duplicated, and the initial object of his anger would highlight a long-standing grudge against the Stark family.
Last: "Maybe it’s time we finished it."
Pym, played by Michael Douglas, was scarred by the loss of his wife Jan during the war, and he attempted to avoid his feelings about her assumed death by not only pushing his daughter away, but also his superhero design work. In the finale of the film, Hank and Hope reconnect as he reveals the half-constructed Wasp costume he had designed, deciding it's time for them to finally finish it.
Mitchell Carson
First: "He doesn't seem happy."
Martin Donovan played Mitchell Carson, who first appeared in 1989 as S.H.I.E.L.D.'s Head of Defense, though he is later revealed to be a Hydra double agent. His comment comes shortly after Hank Pym first interrupts their meeting and showcases his attitude towards Pym that continues throughout the rest of the movie.
Last: "Here we go."
Carson's final line comes as Hope pulled a gun on her boss to protect Pym, and, as a veteran of high-pressure situations as well as his known knowledge of disrespecting Pym from the past, his particular sense of humor shines alongside a sense of preparedness that enables Carson to escape with a vial of Pym Particles intact.
Scott Lang/Ant-Man
First: "You didn't even move."
Paul Rudd's Scott Lang began Ant-Man on his last day in prison involved in a fight with his cellmate in a bizarre final day ritual. While Lang's blow barely even fazed his opponent, he would learn a lot over the course of the film to take on others much larger than his former cellmate.
Last: "And? What'd he say?"
Scott's final words are with his new team as they relay information about a meeting with Falcon, who Ant-Man met earlier in the film while stealing from the Avengers Compound. Ant-Man was a bit of an Avengers fanboy, so his excitement was clear when he asked Luis to get to the point about Falcon's questions regarding Ant-Man.
Hope van Dyne
First: "Good morning, Hank."
Hope van Dyne, played by Evangeline Lilly, works at Pym Technologies and is one of the first characters Hank encounters at the Yellowjacket presentation, and her greeting to her father highlights the rocky relationship of the pair since her mother's death during the war.
LAST: "It's about damn time."
One of the post-credit scenes featured a moment between hank and Hope after they have reconciled over the truth of Jan's disappearance, leading to Hank's reveal of the unfinished Wasp suit that he wants them to finish together. Hope's final line is a multi-layered comment about the Wasp's return, as well as the addition of another female hero to the MCU.
Darren Cross/Yellowjacket
First: "More like, thrilled."
Corey Stoll played Darren Cross/Yellowjacket, a protege of Pym's who took over his company and tried to recreate his technology to power his Yellowjacket program. His first line in the film comes as an interjection in Hank and Hope's conversation with a fake enthusiasm that revealed Cross's two-faced nature early.
Last: "AAARGH!"
While Cross was a dangerous threat in the comics, he was given the Yellowjacket upgrade for the film, which allowed him to fight on an even playing field against Scott lang's Ant-Man. However, Lang got the upper hand and destroyed a key piece of Yellowjacket's tech, causing Cross to cry out in pain as his armor shrunk him out of existence.
Cassie Lang
First: "Daddy!"
Scott's daughter, Cassie Lang, played by Abby Rider Fortson, is the most important person in his life and his reason for becoming Ant-Man in the first place, and Cassie's first line after she sees her father for the first time in years at her birthday party showcases how important he is to her as well.
Last: "Good boy."
As Cassie sat down with her family—including her father, Scott—in the finale of the film, her parents share a video of her performing a cartwheel to Scott while Cassie feeds scraps of food to her new pet under the table; that pet being the ant who was enlarged earlier during Ant-Man and Yellowjacket's battle.
Maggie
FIRST: "Scott! You can’t just show up here, you know that. Come on."
Judy Greer played Scott's ex-wife, Maggie, whose first line to Scott as he crashes his daughter's birthday party sets the tone of their relationship immediately and highlights that, while Scott wants to be a part of his daughter's life, he hasn't earned that right with her mother yet.
Last: "She has been practicing all week, but today was the magic day."
Maggie's final line may not seem to carry much weight, as it is said in a conversation with her family about Cassie's recent success at cartwheeling, but it shows how far their family unit has come over the course of the movie, as she has gone from anger at Scott's presence in her house to a normal, everyday dinner filled with happiness.
Paxton
First: "He didn’t get an invitation! But he came anyway."
Paxton, played by Bobby Cannavale, is Maggie's new partner, and a loving father figure to Cassie. His caring attitude towards her is evident from the beginning, as he manages to cover his disdain and irritation for Scott while talking about him in front of her, though it's clear enough to Scott how he feels about him.
Last: "Oh, well, that’s my pleasure. But no, no, this one, I… I did it for you."
However, after Scott saves both Cassie and Paxton's life from Yellowjacket, his attitude towards Scott has clearly changed as they share a meal together. Scott thanks Paxton for clearing him of the earlier break-out, and Paxton reveals that while he helps Cassie because he loves her, he helped Scott because he earned it.
Luis
First: "Scotty! What's up, man? Damn!"
While Dave and Kurt were each valuable members of Scott's team, it was Luis, played by Michael Peña, who stole the spotlight with his passionate and fast-paced story-telling ability, and his personality was on full display from his very first line as he greets his friend Scott on his release from prison.
Last: "He said yes."
Luis' final words in Ant-Man—and the final lines of the film before the credits—are in response to a question from Scott Lang, though it followed yet another fantastically long recap of the series of conversations that revealed Anthony Mackie's Falcon was putting the word out that he was looking for Ant-Man for his follow-up appearance in Captain America: Civil War.