Aaron Taylor-Johnson, 34, has revealed his close bond with 18-year-old stepdaughter Jessie, known as Phoenix, sharing his sweet nickname for the teen is "babygirl".
Aaron is married to Jessie's mom Sam; Sam also marked Jessie's milestone birthday by sharing a carousel of pictures of the girl over the years, and writing: "18. My darling Phoenix. Happy Birthday. You are everything and more. I love you. I am so proud to be your Mummy."
The pair met working together on Nowhere Boy in 2009 when Aaron was 19 and Sam was 42.
Sam was the director on the title and Aaron played the lead role of a teenage John Lennon who was starting his early music career before becoming part of the Fab Four.
They bonded extremely quickly while working together and it wasn't long before they began appearing together at events as a couple, happily posing for photographs arm-in-arm and sharing a kiss.
"I managed to hold off really until almost the end of the film," Sam later said of acting on her feelings. "Maybe feelings were there but un-acted upon. The thing is, we had quite a psychic link when we were working together. I knew from a flicker of an eyelash what kind of performance I was going to get. I felt that link almost from day one of meeting him."
The couple welcomed their first child together, a daughter named Wylda Rae, in July 2010, and in January 2012, they welcomed another girl, Romy Hero Johnson.
Before meeting and marrying Aaron, Sam was previously married to ex-husband Jay Jopling, with whom she shares two daughters, Angelica and Jessie.
In 2012, Aaron and Sam tied the knot, and for their nine-year-anniversary the pair received matching tattoos, with Kraven the Hunter star Aaron getting a hummingbird flying next to Sam's name inked across his chest.
She also has a matching one with Aaron's name in similar calligraphy near her collarbone.
Addressing their 23-year age gap, he told The Telegraph: "When I met Sam I'd already lived a life far beyond that of most of my contemporaries – I didn't relate to anyone my age. I just feel that we're on the same wavelength."