“They started seeing each other while they were filming Spider-Man,” says the source. “They’ve been super careful to keep it private and out of the public eye but they’ve gone on vacations with each other and try and spend as much time as possible with one another.”
Adds an insider: “They’re both really ambitious and they challenge each other — but, most importantly, they make each other crack up. They seem to have a really similar sense of humor and love joking around together. They have great banter back and forth.”
Shortly before the July 7 premiere of their film, Holland, 21, opened up to PEOPLE about how Zendaya, 20, has helped him navigate the spotlight.
“We are like the best of friends. She’s so great and amazing,” Holland said of his costar. “I’m a little worried [about dealing with fame … but] Zendaya is super famous and she’s been through this and I just call her up and say, ‘How do I manage being famous?’ I’m very glad I have a friend like her.”
VIDEO: Tom Holland Reveals When He Feels The Sexiest
Holland, who made his West End debut in the title role of Billy Elliot the Musical in 2008, and Zendaya, who also stars in Disney Channel’s K.C. Undercover, are not the first Spider-Man costars to have created sparks while filming.
Kirsten Dunst and Tobey Maguire began dating while shooting 2002’s Spider-Man but ended their relationship before shooting 2007’s Spider-Man 3. Emma Stone and Andrew Garfield began dating after filming 2012’s The Amazing Spider-Man. Stone and Garfield confirmed they’d split in 2015 but remain supportive of each other’s career successes.
This article originally appeared on People.com