Isabel Oliver Marcus: Meet Teen Randall's Mystery Girlfriend, Allison, On 'This Is Us'

This Is Us fans have been piecing together clues about the timeline of Jack Pearson's death, and while there have been a lot of theories on how he dies, one thing is for sure: A mystery redhead is sitting with two of his kids shortly after they get the sad news.

On the This Is Us season 2 premiere, after teen Kate and Randall (played by Hannah Zeile and Niles Fitch) were given the news of their father Jack's demise, a previously unseen dog sat on Kate's lap and a pretty redhead was consoling a crying Randall while holding his hand. Fans went crazy, and This Is Us star Mandy Moore confirmed to the Hollywood Reporter that the mystery redhead was Randall's girlfriend.

Now, the mystery of the red-headed girl has been solved. In an interview with Aced magazine, Isabel Oliver Marcus revealed that when she auditioned for the part on This Is Us, her character was simply listed as Red-Headed Teen Girl in the script for the episode, "A Father's Advice."

"When episode 201 came out and we saw her at the very end with Randall, holding his hand, there was a lot of buzz around her," Marcus said.

"The writers and show's creator, Dan Fogelman, said she's part of Jack's death storyline. There were times when they said it's the cast, the dog, and the Red-Headed Girl. We've seen how the first two come into play, and now we see how the Red Headed Girl fits into this story. So we're going to see Randall's girlfriend and the role she plays in the Pearson family drama."
While fans are still waiting to see how a dog, a leg cast, and a red-headed girl play into Jack Pearson's death reveal, the actress who plays the mystery This Is Us character is speaking out—and giving her character a name.

In a new interview with My San Antonio, Isabel Oliver Marcus revealed that she kicks off an emotional four-episode arc as Allison, the girlfriend of teenage Randall Pearson, starting with the Jan. 16 This Is Us episode, "Clooney." This is Us fans will see how Randall meets his first girlfriend during a trip to the mall. Randall will reportedly ask Allison on a first date—with the help of a Magic 8 ball—but Isabel Oliver Marcus is mum on whether not her character accepts his offer in the "Clooney" episode. Still, it's clear that Allison is there for Randall by the time his father passes away.

In an interview with the This is Us Fansided site This is Us Crying, Isabel Oliver Marcus revealed that fans can expect "cute" when they first see Allison and Randall together.

"We'll get to see a little more history, and she gets to be part of the Pearsons' biggest struggle, since of course, she's around after Jack's death, as we saw in my first episode," Isabel said. "However, even I don't know all of where it's going."

According to Isabel Oliver Marcus' IMDB page, she is a native of Texas who grew up in a diverse neighborhood full of creative types. An only child, Isabel collected boxes of costumes purchased from thrift stores and constructed characters by dressing up sticks and flowerpots before forcing her parents to watch her solo performances. Isabel went to high school in San Antonio through her sophomore year, where she studied musical theater at North East School of the Arts. In 2016 Isabel Oliver Marcus permanently relocated to Los Angeles to pursue a serious acting career.

In an interview with the Movie Waffler, Isabel described This Is Us as her first "big gig." She also admitted that she was in the dark about some aspects of the Allison character so she had to "build" them for herself.

"There has even been some stuff that I decided about her for myself, and then got a script, and found that the writers had had the same idea," Marcus said. "For instance, she likes to bake. I can also tell you she's sweet, smart, and that she's Randall's girlfriend. But I guess you already knew that."

Check out the video below to see Isabel Oliver Marcus talking about her role on This Is Us.

This Is Us airs Tuesdays at 9 p.m. ET on NBC.