Tonight, the Grey's Anatomy and Station 19 crossover event brings some of Seattle's finest firefighters to Grey-Sloan Memorial, taking a leaf out of Dick Wolf's One Chicago playbook, and it all centers on a kid. Well, not just one kid — as these shows tend to go, there's a common thread in tonight's episode(s), and "Momma Knows Best" is all about the little ones in everyone's lives.

Let's start with Meredith Grey (Ellen Pompeo). Per Cici's recommendation, she's going out on a fixed date, and the matchmaker's process is a little unorthodox. Meredith knows very little about her date, and all he gets is a picture. She's dolled up enough that she has everyone's jaws dragging the floor (both Ortho God Link and Hellmouth seem particularly intrigued by the gussied-up Dr. Grey), and her date John (played by How I Met Your Mother's Josh Radnor) doesn't recognize her. The reason? It's not just the extra makeup. She's not the one he was supposed to be meeting tonight. Halfway through their date, which is going surprisingly well, he spots his intended date over at the bar having a great time with Mer's Dear John, and they decide to let the two proceed unaware.

<em>Grey's Anatomy</em>, ABCGrey's Anatomy, ABC

The reason they decide not to break up the other party is that Meredith's having an unexpectedly great time with John. She even loses a bet with Alex Karev (Justin Chambers) to keep things moving and grooving with their conversation. The pros: John shares Meredith's workaholism and respects her accomplishments; also, he might be in a very different field — he sets up privacy protections for people online — but he's still doing a good service for people. The con: He doesn't want children because he's afraid they'll hold him back. Talk about a deal-breaker. Meredith kindly tells him that she has children, doesn't consider them to be holding her back, and thanks him for a fun time.

John looks immediately remorseful of his words as she walks away, knowing full well he has "said the thing" that turns a date into a disaster. Whether or not we should officially call time of death on this relationship remains to be seen, though, because considering how well the two meshed on every other issue, there's still a possibility for romantic resuscitation.

Meanwhile, Amelia Shepherd (Catarina Scorsone) is having a heck of a time adjusting to being the pseudo-adoptive mother of Betty (Peyton Kennedy). With baby Leo, it's easy to get used to his changing diaper size and sleeping schedule. But with Betty, she's jumping in feet first, and the girl's a recovering addict to boot, so Amelia's especially on high alert at all times.

To be fair to her, Betty's not making it any easier on anyone. In response to being accused of doing drugs, she calls Amelia a "hag" twice and storms around everywhere she steps. The ingratitude is frustrating to Amelia and Owen Hunt (Kevin McKidd) both, but especially for Amelia, who doesn't exactly know what her role is supposed to be for this girl. She wants to treat her like a sponsor and force her to take a drug test at the hospital, but thanks to a cameo appearance by Mama Hunt (!), she realizes she needs to be a mother to the child instead, no matter how much they both resist that title.

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Once Betty fesses up to smoking weed with a friend, Amelia puts back on the addict hat to remind her that every substance is a gateway for people like them, but she resorts right back to mom mode and gives the girl a hefty grounding as punishment, merrily accepting Betty's assessment that her ish-parents are "lame." Teenagers!

Karev's subplot is pretty interesting as well, as he's finally starting to see the perks of being the chief — he can get away with questionable ethical calls because the only one anyone can report it to is ... himself. He uses that newfound power for good, of course. By nicking a kid who has a congenital condition that his overworked mother can't afford the treatment for — and there's a stinging rebuke of the pre-existing conditions problems with insurance coverage in there for timeliness' sake — he's able to dub it an emergency surgery and offer the kid a better present and future. Not all heroes wear capes, guys.

The kid who really needs saving tonight, though, is Max. His mother was evacuated from the fire that brought Station 19 to the hall of the hospital, and while she wasn't endangered by the smoke or flames, she suffered a heart attack that caused so much damage even Maggie Pierce (Kelly McCreary) is unable to repair her. Max is already skiddish enough about being in the hospital, so his father makes the decision not to tell him how bad off his mom is. He's really banking on that "slim chance" of recovery Maggie mentioned.

<em>Grey's Anatomy</em>, ABCGrey's Anatomy, ABC

While Dr. Pierce is off fielding date offers from Firefighter Dean and warring with herself over whether she should warn Amelia and Owen about the sure-to-be-a-bomb-drop news that Teddy Altman is pregnant with his baby, DeLuca accidentally tells young Max about his mother's true condition, and he sprints off.

The police manage to track the boy down, but he falls into a drain pipe during the foot pursuit and the whole fire department has to get involved. Well, everyone except Ben Warren (Jason George), whose tough new chief is taking him to task for taking off his glove during their earlier rescue op and subsequently patching himself up like he's still a surgeon by trade.

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Naturally, things get pretty dramatic from there — when they finally do find Max clinging on for dear life, Herrera makes the mistake of jumping into action in the rushing waters below another entry point, and it actually sets their search and rescue mission back when he's rushed away. Fortunately, the squad is eventually able to find another access point, his dad talks him down from giving up by being honest about his mother's true peril, and the boy is saved. It's a bittersweet moment for everyone, considering these two guys are still facing the insurmountable with his mom.

The situation spurs Maggie to break her promise (and HIPAA) not to tell Meredith about Teddy's pregnancy. She justifies it by saying that some hard truths just need to be told in advance. So, while Amelia and Owen have just painstakingly figured out how to deal with the two kids they've got in their care already, they're about to have to navigate another kind of co-parenting situation altogether.

You know what? That guy John was right; kids are complicated.

Grey's Anatomy airs Thursday nights at 8/7c on ABC.