9-1-1 's Buck finds it harder than anticipated to be a sperm donor: 'I'm abstaining from everything '

When EW spoke to 9-1-1 star Oliver Stark at the start of season 6, he promised that his character Buck would be "really put to the test" — but we didn't expect it would play out like this.

In an exclusive preview clip from tonight's episode of the Fox first responder drama, Buck reveals to the 118's newly reinstated paramedic firefighter, Hen (Aisha Hinds), that he is going to donate sperm so his college friend Colin and Colin's wife can have baby.

Buck is eating healthy and abstaining from anything that could affect his "swimmers" — and he means anything. The gesture is kind, but proving frustrating due to various comedies tragedies of error that have made the process take "longer than expected."

Stark teased this sperm donor plot line in our interview back in September, saying Buck would face "some really big life decisions that he never expected to be faced with being dropped on his plate." He also reflected on how much his character has grown since breaking up with Taylor (Megan West) at the end of season 5: "He's certainly over his breakup, which obviously was his decision, but that doesn't mean it's always easy. I think he's really working on himself, and growing into a person that is ready to take on more responsibility and become the kind of firefighter that he wants to be."

That responsibility appears to include becoming a biological father — though not getting a couch just yet, it seems.

Season 6, episode 7 of 9-1-1 — titled "Cursed" — airs tonight at 8 p.m. ET on Fox.

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