'This Is Us' season 1 spoilers, news: Series creator teases bigger Randall and William's storylines

After giving out a major clue on Jack's (Milo Ventimiglia) death, the upcoming episodes of "This Is Us" will focus more on Randall (Sterling K. Brown) and William's (Ron Cephas Jones) respective storylines.

Series creator Dan Fogelman recently spoke with TV Guide, and he revealed that the remaining episodes of season 1 will mainly explore William's fight with cancer. "Different answers are searched for, and different possible outcomes are on the table. In terms of Randall's storyline and William's storyline, our focus really turns to that," Fogelman teased.

A previous episode already gave viewers a glimpse of William's son, Randall, in mourning, which pretty much means William's death is inevitable. In the show's current timeline, William appears to have a more positive outlook in life due to what Randall's wife, Beth (Susan Kelechi Watson), called a "chemo boost" after he refused to have any treatment. While William's passing is, unfortunately, imminent, Fogelman revealed that he won't be exiting the story anytime soon.

Aside from his health, the next episodes will dig deeper into William's backstory and his relationship with Randall's biological mother. "The Leftovers" actress Amanda Warren has been tapped to guest star as William's mother, Dorothy, for a flashback episode centering on William's younger years. "Atlanta" actor Brian Tyree Henry will also guest star as William's cousin.

Warren has starred in many notable TV programs, including "The Closer," "The Good Wife" and "Gossip Girl." The actress currently recurs in NBC's pilot drama "Taken," which will air next month, and appears in Netflix's political drama "House of Cards."

The 34-year-old actress joins the roster of "This Is Us" guest stars this season that includes Seth Meyers, Gerald McRaney, Katey Sagal, Alexandra Breckenridge, Jimmi Simpson, Brad Garrett, Janet Montgomery and Sam Trammell. Katie Couric is also guest starring on a new episode, but compared to the other actors, she is set to portray herself.

The first season of "This Is Us" airs every Tuesday night at 9 p.m. ET on NBC.