Two years ago, writer and director James Gunn and his cranky, lovable band of multihued misfits in space seemed like a sort of gamble for the Earth-bound Marvel Studios and its ever-growing plans for total multiplex domination. Star Lord wasn't exactly a household name, and neither was Chris Pratt.

Now as "Guardians of the Galaxy Vol. 2" prepares for launch in North American theaters on Friday, the story is quite different. "Guardians of the Galaxy" was a huge critical and financial success, grossing over $773 million worldwide, Pratt became an international star, and Gunn was given the greenlight to do what he wanted once more - making "Vol. 2" as weird and wild and idiosyncratic as his imagination would allow. Many reviewers have already called "Vol. 2" better than the first, the monosyllabic Baby Groot is already a breakout star, and it's headed for a possible $140 million to $150 million opening weekend.

"So many sequels are not good," Gunn said. "We really tried to let these characters grow and change. ... I didn't want it to be a rehash of the first movie."

Gunn likes to say that "Vol. 2" is an adventure film, a comedy and a space opera tied up into one brightly colored package, but that at its core, it's a family melodrama. A lot of big action and sci-fi films claim to be about family - whether it's the people you're tied to by blood or the ones you choose - but it's often a lot of talk. "Guardians of the Galaxy Vol. 2" might have a talking tree and a wise-cracking, machine gun-toting raccoon and an unparalleled glee for the art of teasing, but it's also got a big, beating heart that actually hit quite close to home for both Pratt and Gunn.

Pratt's Star Lord/Peter Quill meets his father Ego (Kurt Russell) for the first time in "Guardians 2" after a lifetime of explaining away his absence telling people that his father was David Hasselhoff, while being raised by the scoundrel Ravager, Yondu (Michael Rooker).

A lot of the story, which also includes a sisterly rivalry that has veered into the murderous zone, is drawn from Gunn's relationship with his father, a recovering alcoholic who has been sober for 20 years, and what he calls his big, lovingly dysfunctional Irish Catholic family. And even though it's his life on the page, there was one person he needed to get to sign off from first: Pratt.

Pratt's father died in 2014 after battling multiple sclerosis for years - a condition the once hard-working, tough love, man's man Dan Pratt refused to treat. In 2015, Pratt told GQ magazine that it eventually led to him splitting up with his mother and living out the rest of his days in front of the television in assisted living.

"(Chris) was the first person I told it to, that's for sure. When I came up with the story, Chris came over to my house and I said, 'OK, here's what I'm thinking about,'" Gunn said. "I wanted to make sure he was onboard with it because, I mean, there's a lot of personal stuff there. I wanted to make sure he was cool with it."

Pratt said he related to the story a lot. His dad, he said, was not dissimilar to Yondu in the way he showed love. Cat Stevens' "Fathers and Sons" even plays at a pivotal moment.

"All of it is completely honest and true even though it's about aliens," Gunn said. "It is honest and true stuff about human beings and the way we interact and how we have a hard time accepting love from other human beings."

This little cobbled-together family is not disbanding yet, either. Gunn, who has done nothing else but work with these characters for the past five years of his life, will continue stewarding the Guardians through their trials in "Avengers: Infinity War," where he says they are "supporting characters but not small roles." He's also signed on for "Guardians of the Galaxy Vol. 3," which will close out that series and launch Marvel into its next decade.

"With the first movie, James earned Disney's trust," Pratt said recently. "On the second movie he was like, 'I'm going to do whatever I want with all of your money.' And they said, 'OK.' And he made the craziest movie."

Gunn even said he was a little timid on the first film, but not anymore.

"I'm a little punk rock kid who likes edgy stuff. I thought what I liked might not be what the entire world likes," Gunn said. "But I've come to trust that what I like works."