The final episode of “This Is Us” revealed that Kevin had a preteen son, but the fact that he had just broken up with Zoe in the present-day timeline left viewers wondering how he had ended up with one. In a recent interview, Kevin actor Justin Hartley teased that the mystery surrounding the son’s mother would be one of the most compelling mysteries next season.

With the identity of Kevin’s son’s mother still unknown, it is clear that another puzzle is brewing for the next season. According to Hartley, this puzzle will come together in a way that will definitely satisfy the audience. “It’s one of those standard ‘This Is Us’ writer moments where when you see it, you go, ‘Why didn’t I see that coming?’” he said. “But you can’t see it until it’s in front of your face,” he added.

Hartley revealed that the storyline surrounding the kid, Kevin’s future and where he is headed next season will be a bigger story than how he was in the pilot. He also teased that when it comes to his son, there is a chance that he is not his only child or that he is not his child. Most of Kevin’s story, he said, has yet to be told.

As to whether or not Kevin and the mother of the child are still together, Hartley admitted that even he could not tell. “As far as the audience goes, we know absolutely nothing,” he said. “I mean, did he find this kind? Did he adopt this kid? Did he get married? Did he have this kid out of wedlock?” he continued.

He added that Kevin could also have more than one child. “It just seems like it’s wide open for an amazing story to be told,” he said.

As for Sophie, Hartley neither confirmed nor denied when asked if there is going to be a reconciliation between Kevin and his first love next season. While he did not reveal that Sophie could be the mother of his child, he did not drop any major detail. However, he said that there might be more story to tell between Kevin and Sophie despite how they ended up last season.

Meanwhile, “Once Upon A Time” alum Jennifer Morrison just joined the cast of “This Is Us.” The actress has yet to confirm her role in the series, but speculations are rife that she might be the mystery mother of Kevin’s child.

This Is Us 'This Is Us' returns on September 24 on NBC. Facebook/NBCThisIsUs