Grey’s Anatomy: Meredith Meets Nick’s Estranged Sister as They Reunite After 8 Years, but There’s a Twist (Exclusive)

A surprise arrival brings some family drama for Ellen Pompeo and Scott Speedman on Grey’s Anatomy this week.

In PEOPLE’s exclusive clip from the Thursday, Jan. 22 episode of Grey’s Anatomy, Meredith (Pompeo) and Nick (Speedman) are awaiting the arrival of a special guest — Nick’s estranged sister, Erica (Brit Morgan), who he hasn’t seen in eight years.

He’s preparing an elaborate spread for his sister as he anxiously awaits her arrival, and he tells Meredith that he’s “giving [Erica] the benefit of the doubt.”

Meredith points out that eight years is quite a long time to go without speaking to someone, sibling or otherwise, to which Nick shares, “Well, in my defense, a lot of that time, she was drunk or high.”

“But Charlotte says she’s doing really well,” Nick tells Meredith of his sister. “She’s sober and she has a new project or something.”

Despite their current estrangement, Nick says that he and his sister “used to be really close — especially after we lost our mom.”

“You know, when she’s not detonating our lives, she’s actually really funny. She’s a lot more fun than I am,” he says.

When the doorbell rings, alerting them of Erica’s arrival, Nick is shocked to find out his sister is not alone. “Hey, big brother,” she says, carrying a newborn in a baby carrier.

A shocked Nick asks, “Erica, who’s this?” and she tells him, “This is Miles, my son.”

It’s a revelation Nick was not expecting — nor does he look too happy about it — as he welcomes his sister into his home and the clip ends.

Speedman, 50, first joined Grey’s as a guest star in season 14, but returned in seasons 18 and 19 as a love interest for Pompeo, 56.

Ahead of his return, the Felicity alum told PEOPLE he was “excited to be back” on set as he teased Nick’s romance with Meredith. “I don’t know where it’s going, but I get to explore the character more and we can really draw things out.

“It’s really fun to slip back into a romantic role,” he said.

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Pompeo, too, was excited to welcome him back. “Scott’s a great actor. He’s interesting, edgy, sexy and super present,” she told PEOPLE. “We have great chemistry, we’re having a lot of fun filming our scenes and I know the audience will feel it.”

Since season 19, he’s been a recurring star on the show as Nick and Meredith’s romance has continued to blossom.

New episodes of Grey’s Anatomy air Thursdays at 10 p.m. ET on ABC and stream the next day on Hulu.