Outlander: Blood of My Blood star Jamie Roy officially has Sam Heughan's stamp of approval.

Roy plays Brian Fraser, the father of Heughan's Outlander character Jamie Fraser, in the new prequel series. He and Harriet Slater tell the story of Jamie's parents falling in love in 18th-century Scotland, while Hermione Corfield and Jeremy Irvine are parents to Claire (Caitriona Balfe) and explore their origin story during World War I.

Stepping into such a beloved franchise was a daunting task for Roy, and he tells PEOPLE why it mean so much to have Heughan, 45, in his corner.

"Sam has been nothing but supportive since the very beginning," Roy says.

"I'll always remember his advice," Roy shares. "[He told] me just to appreciate every moment, even on the tough days, because it goes past so quickly."

Heughan also attended the show's premiere in Los Angeles on July 28. Roy says he was "really glad" that the actor could be there.

"It meant a lot to me how much he enjoyed it," he admits.

"Looking back, I believe that everything happens for a reason. We have this saying in Scotland: what's for you won't go by you. And I really believe that is the case," he says.

"I'm very glad it happened this way, for the obvious reason that the role of Brian Fraser is significantly bigger than militia man number one."

He continues, "But also I believe that it serves as an inspiring story to other actors who may feel like they send their additions out into the ether and never hear anything back. Because you never know what is happening behind closed doors."

"Since the very beginning, I've had nothing but lots of love and support, not only from fans but also the showrunners Matt and Maril," he says.

That support has "allowed me to really explore the character organically as the season has gone on."

He also praises his scene partner, Slater, who he says he vibed with "straight away" as he dishes on how they built their chemistry to play love interests onscreen: "When I first met Harriet, I knew that we would get along."

"That friendship that started on the day of our chemistry test has only grown deeper as we've gotten to know [each other] and work together more," he adds.

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