Aaron Taylor-Johnson is one kick-ass stepdad.

The Fall Guy star—who married Fifty Shades of Grey director Sam Taylor-Johnson in 2012—shared rare photos alongside his stepdaughter, Jessie Phoenix Jopling, to celebrate her 18th birthday.

In an Oct. 8 Instagram Story, the actor—who, along with Jessie, is also stepdad to Angelica Mara Jopling, both from Sam’s first marriage to Jay Jopling—held on tight to a young Jessie in a throwback pic, captioning the snap by writing, “Happy Birthday BabyGirl.”

In a second Story, he then shared a photo of himself hugging the birthday girl in a field as he pursed his lips for the camera. Alongside the sweet selfie, he wrote, “18 now ..still my babygirl.”

And while parenting certainly keeps the Bullet Train star— who also shares daughters Wylda, 13, and Romy, 12, with Sam—busy, he previously credited his home life with keeping him disciplined in the gym.

“Almost weirdly, I think my workout time kind of is my unwinding time in a way because it’s my time, which feels very rare these days,” he told The Hollywood Reporter in January. “If you get an hour and a half yourself, it feels very much like a wind-down time because you’re able to have your own thoughts for a minute and decompress and sort of set yourself straight again and realign yourself.”

And the Tenet actor, 34, is proud to show off his gains in the gym. After all, he proudly flaunted the results of his fitness regimen on a recent romantic getaway with Sam, 57, posting a photo of him baring his six-pack abs in not one, but two shirtless shots. Alongside the photo, he wrote, “little get away.”

Another aspect of Aaron’s home life that may surprise fans? His 23-year age gap with Sam, who first met her future husband while directing him in 2009’s Nowhere Boy. In fact, Aaron has said he’s unfazed by questions about their relationship.

"And it comes up on the outside perspective of people who don't know us, because I guess people will always…” Sam told The Guardian in April. “We're a bit of an anomaly, but it's that thing: after 14 years you just think, surely by now it doesn't really matter?”

For more on their romance, read on.

Love at first read? “I wasn’t expecting anything that day," Sam Taylor-Johnson told Harper's Bazaar of future husband Aaron Taylor-Johnson's 2008 audition for her directorial debut Nowhere Boy. "Just to see a bunch of actors pretending to be John Lennon.”

The 18-year-old impressed in more ways than one—nabbing the role and eventually the director's heart. "I knew instantly," she later told The Telegraph of him nailing the read. "I could see how much research he'd done already just by the way he was standing and the few words he said."

Though she would later tell Harper's Bazaar they "were very professional through the entire film," after they wrapped, she continued, "He told me he was going to marry me. We had never been on a date, or even kissed.”

Precisely one year after they met, he shared, "I got down on one knee and asked her to marry me.” The pair announced their engagement at their film's London premiere. 

By the time he was 11, Aaron recounted to Esquire, he was already planning for a big family. So not only was he ready to embrace the role of stepdad to Angelica and Jessie, Sam's daughters with ex-husband Jay Joplin, but he was eager to add a few of their own. 

"I knew I was going to be a young father," he explained. "I knew I was going to have many kids.” The couple welcomed daughter Wylda in July 2010. 

Receiving an OBE recognizing her artwork and photography from the future King Charles III at Buckinham Palace, Sam brought along Aaron and her eldest daughters. 

A year and a half after Wylda's birth, daughter Romy joined the team in January 2012. "The great thing about Aaron is that he's happy not working and being at home with the kids while I work," the director told The Guardian in 2015. "We're actually fighting over it. He's like, 'No no, I like being an at-home dad, doing the cooking and the school runs.'"

Months after their June wedding in Somerset, England, the couple (at the London premiere of Skyfall) revealed they'd decided to combine their last names into one. 

"I just don't see why women need to take the man's name," Aaron explained to the London Evening Standard. "I wanted to be a part of her just as much as she wanted to be part of me."

Mrs. Taylor-Johnson will see you now. While promoting Fifty Shades of Grey, the director raved about her years-long romance.

"Being in an amazing relationship, having come out of a difficult one, it felt so good," she noted to The Guardian. "And I feel like that stability has enabled me to get on with doing this momentous project."

But, no, she never once considered casting her man as Christian Grey. "We both read it and knew right then that when she went into direct it, I wouldn't be the one to step into those shoes," he told Marie Claire U.K. "And that was fine. It didn't feel like one of us was like, "I really wanted to do that'...I'm obviously really, really proud of Sam and it was great to see her take that project and make it her own, and not have to feel like just because there's a role...I feel like I'm too young for that role anyway!"

When the actor won his first Golden Globe, as the star of Tom Ford's Nocturnal Animals, he shouted out all of his girls. 

"I want to thank my wife for being there with me, supporting me through this," he said. "Thank you for putting up with me. Jesus, that was not very pleasant in this role, so you're my soulmate and I love you very much."

"I'm blessed," he continued. "I have four beautiful daughters: Angelica, Phoenix, Wylda, and Romy, I love you all very much."

Before teaming up for A Million Little Pieces, the duo teased their future plans. "We are definitely working towards something interesting," Aaron told E! News at the 2017 Santa Barbara International Film Festival. "Hopefully we can get it off the ground. I mean, this is the best director right here I'm desperate to work with again."

Forgoing the traditional tin, the pair celebrated their 10th wedding anniversary with a vow renewal. "Yesterday was the most beautiful day, summer solstice, our 10th anniversary," Aaron wrote, sharing the photos on Instagram. "We renewed our vows to one another and confessed our love in front of our nearest and dearest friends and family it was a celebration of love and joy!"

Echoed his bride, "10 glorious years. My incredible husband, father to all 4 girls. I love you, I love you, I love you."

While the stars (at the London premiere of Back to Black) are aware others want to address their age gap, "When you're solid with someone in your own love," she told The Sunday Times, "you don't think about it." 

For the latest breaking news updates, click here to download the E! News App