Brace yourselves for emotional whiplash tonight, people.

Grey's Anatomy has had plenty of sappy moments, and just as many happy ones, but tonight we're getting the full buffet of emotional options, from the new love jitters to the protective parent stuff all the way on down the line to full-on mental breakdown mode. It's ... a lot. Let's start with the lighter stuff and work our way through, then, shall we?

For starters, there's Bailey (Chandra Wilson), who adopts Jo (Camilla Luddington) to her service for the day to treat a former NASA physicist who's now spending her time in the desert trying to create a wormhole through time. Yes, really. All that experimenting has cost her dearly, though, as she's admitted with some blunt-force trauma that's going to require some surgery and, ultimately, results in a bleed-out.

Mad props (emphasis on mad) to her for paving her own way, though. They've gotta respect her moxie, and, hey, the theme gives Bailey an idea for what to name her own little medical breakthrough (break-wind-through?) in the colonoscopy device. Ms. Marge also inspires Jo to put her foot down with Meredith (Ellen Pompeo) about letting some relic of her own past come back to commandeer her own proverbial ship.

As Miranda reminds everyone so many times, you can't go back in time, so the past can only come to you. In Mer's case, she's letting Ellis' legacy stand in the way of her acquiescing to Marie Cersone's terms and getting her hands on that polymer. She doesn't want to betray her mother's memory by admitting that she was some kind of friend-traitor even though (1) that woman was definitely cutthroat enough to do something exactly like this and (2) Mer's suffered from her choices quite enough (as she puts it to Maggie, "You've never had your hopes and dreams crushed by our mother, but for me it was an annual event").

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At Jo's insistence, though, they'll at least start to explore alternative options for the particular type of polymer involved in their procedure, even if, as Mer has claimed, it's a fruitless endeavor in the face of all that money and equipment Cerone's business has at its disposal. Hey, you don't win Harper-Avery and/or this new contest, whatever it shall be named, by sitting on your hands. Besides, this time Jo/Brooke actually gets to put her name on it, so double win!

Meanwhile, Jackson (Jesse Williams) and Maggie (Kelly McCreary) are moving both swiftly and slow as snails all at once. They're this close to declaring themselves to one another, and yet they couldn't tell you what the other's sheet thread count is just yet, nudge nudge. They're ready to take their physical aspects to the next level, of course, but when his mother and Richard Webber (James Pickens Jr.) catch them making out in the supply room, their reaction is less than enthused.

The Avery-Webber fam is all set to scrub in together for that revolutionary new vaginoplasty surgery with Dr. Velez, and yet, Katherine's more concerned with embarrassing Jackson over his choice of mate and how they maybe are-maybe aren't step-siblings now. Velez can see right through all that bickering and doesn't want them to touch her nethers until they've resolved their issues, which basically forces the trio to come to terms with what's really achin' everyone about their budding relationship.

For Webber, it's Katherine's disgust at the idea of Jackson and Maggie that makes him mad; he may not have been her father for long, at least that he knew of, but a girl's daddy doesn't suffer insults like this, and he won't be the first one, no sir. He storms out and lets the Averys hash it out from there. That's when Katherine admits that it's not about Maggie. Maggie's lovely and smart and all of the things, and Jackson's right — their siblinghood is in-name-only. But if Jackson starts seeing Maggie in any meaningful way, it can cause an eventual rift between herself and Richard, if they're ever made to take sides on an argument. Her marriage is so precious to her — well, now that he's sleeping at home again, at least — that she can't let an argument like that come between them. This from the same woman who let months of the silent treatment ensue over the hiring of Eliza Minnick? Pulease.

Jackson recognizes this is as pure histrionics and tells her to take Richard/Maggie's side in the case of an argument, and they get down to the business of using peritoneal tissue in Velez's ladybits to see how it goes.

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Annnd now we're diving into the sticky stuff, folks.

Arizona (Jessica Capshaw) decides to stage a bring-your-daughter-to-work day after Sofia reveals she's bummed out about missing New York and Callie (probably not Penny though). She does rounds with her and even sits in on a pretty gnarly exam. An expectant mother needs Arizona's help keeping her second trimester fetus from coming out way too soon, and in the process of putting out that fire, Robbins discovers that her school-age son Noah has a tick that probably means something terrible.

His laughter is a little too frequent to be genuine, so she orders an MRI on him, just as our poor mom has to go under the knife to put baby humpty-dumpty back atop the metaphorical wall in her belly. As Amelia (Caterina Scorsone) and Alex (Justin Chambers) discover, the kid does indeed have a tumor. And, as these things tend to go on this show, it's inoperable ... unlesssss!

That fancy new laser procedure they've been working on for Kimmy down the hall just might work for our new pal Noah here. Sure, it's risky, since they've yet to even try it on a human being before (and we saw how those test runs on inanimate objects flamed out, so to speak). But it's about the only chance the kid has, so Arizona concedes that they can deliver this great news to the woman who's just dodged a heartbreaking miscarriage. All's swell in Grey Sloan today, yeah?

Oh, it gets worse. So much worse.

The tumor kid gives Amelia the perfect metaphor to use to describe why she and Owen (Kevin McKidd) would have never worked as a real couple. Sure, they have great physical chemistry and obviously know how to push each other's buttons in all the right ways, but by his own admission, when he ran off into Teddy's arms, it was because she was more than just a warm body. She was that friend he never took it there with before but always wanted to. She was his "person," as Mer might say. Amelia's done holding him back from that and sends him on his way to go pick her up, "no feelings" my foot.

Let's just hope Amelia didn't really develop some newfound affection for Owen in the process of all their little romps because we do not need an Amelia Shepherd sobriety slip plot line to pop up again, do we? But speaking of backsliding, the real kicker is April Kepner (Sarah Drew), who's been unraveling at a spectacularly alarming rate all season.

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Her shaken faith in God is informing her every move through the hospital, for better or worse. She begs Owen to let her join his trauma certification training detail, and she turns the situation into absolute chaos. Sure, she's probably got a little PTSD of her own to blame for it all, considering her service overseas, but a lot of it also stems from the fact that she thinks by drenching the interns with waterhoses, screaming at them, and throwing new obstacles at them every time they start to get it right, she's helping them somehow.

She cut corners during her certification and lost a patient a few months later. "There are no rules," she repeats, echoing a similar sentiment she's been carrying about how the wicked are rewarded and the just are punished and nothing is fair because her God has checked out.

When Jackson runs across her in the hall at a particularly rage-y moment, he recognizes that she's broken and ready to burst and asks what he can do to help. That's when she tries to kiss him — it's not about him, per se, sex has just been her go-to comfort zone lately. When he turns her down, she storms out and leaves him in charge of their daughter. There are other guys out there who are willing to take his place, and she wants him to know it.

Things are getting ugly with April, and there are only so many ways out of this kind of thing. Let's just hope she finds her peace sooner than later and doesn't do anything reckless ... well, more reckless than she already is.

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