Last time on end already, Cecily gave birth.

Evil mad scientist evilly grabs her baby and resuscitates it (evilly) while everyone else stands around gaping like idiots.

“Congratulations,” Vaughn says, holding the writhing child up in his gloved hands. “You have a son.”

Then why was Rhine going on and on about how he’d murder it if it was a granddaughter? I assumed that was because they knew the gender from all the ultrasounds.

“Where’s my baby?” Cecily whispers. Her eyes are glassy and distant. Tears and sweat roll down her face. Her breaths rattle in her chest.
“We’ll see him soon, love,” Linden says, and kisses her.
For the moment she looks nothing like a child. If I didn’t know either of them, I would almost believe that they were a normal mother and father in a normal hospital under normal circumstances.

No you wouldn’t, because she’s a thirteen year old girl. She never “looks nothing like a child”. A twenty year old and thirteen year old never look like a normal relationship. STOP IT.

Then Rhine switches over to worrying about Cecily. This might seem out of character, but it’s because in this case, worrying about Cecily is an excuse to bitch about evil mad scientist not taking her to a real hospital, not to in any way imply that maybe the rapist shouldn’t have fucked a thirteen year old or anything.

Also, it’s obvious that evil mad scientist would have all necessary medical equipment here, given how much he likes having the place be self-contained. And the chance of infection is much lower than at a hospital, which are extremely well bleached cesspits of unkillable bacteria.

What if giving birth was too traumatic for her small frame and there are complications?

Rhine, she was gushing blood. I know you’re lazy and suck at basic problem solving, but that’s a complication. There is no “what if” here. It was and there were.

She then goes on for a while about how she doesn’t have any chance to go see Gabriel now, and in passing mentions that by the way, evil mad scientist walked off with the kid and is keeping it in the basement and might murder it any second. Also, she can’t see Gabriel.

Because she’s a terrible protagonist, it doesn’t occur to her to say to evil mad scientist that she’d like to sit with the baby, giving her an excuse to go down there.

(From the sounds of it, it’s likely evil mad scientist is concerned the kid may have inhaled amniotic fluid, since he seemed to need to clear the kid’s throat to get it to breathe. That’s why doctors wouldn’t give me back to my mother, and I’m pretty sure it wasn’t because they were evilly planning evil but because inhaling gunk into your lungs is bad.)

Hours later the rapist goes down to see his kid and is all happy. So naturally he wants to fuck her.

The characterization here is surprisingly consistent. When a lot of men talk about viewing labor, they often see is as traumatic and painful. Their basic empathy kicks in and they imagine having to pass a huge lump through their genitals as they stretch and tear. They’re really happy about the miracle of life and all that came out, but their thoughts are not, at this instant, “Awesome! Let me fuck you so you can do that again!”

The rapist, on the other hand, is so turned on by this. That’s what women are for, to do things for him.

Then he gets on the ledge beside me, and I curl my knees to my chest to make room for him. He smiles at me, and I sense him advancing.
Gently he moves my legs from between us, and my feet land on the ground, and he tilts my chin and kisses me.
I allow it, because I’m first wife—the key card makes it as official as it could get—and because I promised him I’d be a better wife, and it would make him suspicious if I pushed him away. And because, truthfully, it isn’t the worst thing in the world to kiss Linden Ashby.

TVtropes claims in Marital Rape License that:

There are two basic ways in which this can come into play as a trope:
Type A is when a character or group of characters clearly are guided by this kind of morality, but this is not portrayed in a positive light. On the contrary, it is used to define them as villainous or at least severely flawed. In contemporary works, all examples of this trope can be safely assumed to be Type A unless otherwise noted.
Type B is when the narrative itself buys into the morality: It is portrayed as if the woman had it coming for denying her husband his marital rights. However, she still doesn’t enjoy it: If the wife seems to be happy with the forceful sex, then it’s an entirely different trope, and yet another trope if they had agreed on it rather than her being okay with it retroactively. This Type B of the trope typically only comes up in older works. 

Unfortunately, and perhaps an expected oversight for the site, this is referring to violent rape and/or unusual types of sex, which is what the majority of examples listed involve. So while believing it’s okay to beat your wife first may be confined to older works, the perception that wives owe sex is not.
Because she doesn’t immediately shove him off, he starts trying to take her nightgown off. Rhine decides she’s not ready to go that far.

“Is it because the door is open?” he asks. “I’ll close it.”

I have a sinking feeling this is supposed to be a sign of how considerate he is.

Then he starts saying he loves her and wants to have a baby. Rhine attempts to switch things to the subject of all the other stuff she wants to do with him, like seeing houses built and going to parties.

The romance is draining from his face, replaced by confusion or disappointment—I can’t tell which.

Spending time together and sharing interests is unromantic, unlike fucking someone because you just want to collect babies.

He looks heartbroken, though, so I give in and sit close to him and let him put his arm around me. He loves me, he says, but how can he when we know so little about each other?

No, book. It’s not that he doesn’t know her. It’s that he doesn’t love her. His other wife just had a kid and instead of spending his time with it he’s trying to fuck another one into being.

Rhine says that she doesn’t have long before he’ll get suspicious she’s refusing to have sex, so she guesses she should try to escape soon. It’s only taken almost year for her to figure that out.

The next day she notices the servants are being unusually fawning, and Jenna explains it’s because she’s first wife now. This doesn’t actually make sense but I’m sure the author will forget about it soon anyway.

Cecily’s still messed up from the birth.

She’s lost too much blood. That’s Vaughn’s diagnosis, and I agree, but I’m still uneasy when she’s given the transfusion. I lay beside her as she recovers, as the color slowly returns to her cheeks, and I wonder whose blood is coursing through her. Maybe Rose’s. Or some unwilling attendant’s. I wonder if Vaughn, who I believe is capable of such darkness and destruction, ever truly uses his abilities to heal.

So he says the problem is X, and she agrees it’s X. He does the correct procedure to deal with X, and she bitches about it. She watches the procedure fix X. Then she says that he’s evil and doesn’t really heal people.

Does the author think this is sympathetic or reasonable? What the hell is she trying to get across here?

Rhine then says that Cecily’s fine and happy and she’s sure they’ll have a wonderful life together and that’s why it’s important only she escape.

Later, Cecily takes the baby out when she decides to play on the piano.

Her son makes uncertain faces and wriggles in place, unsure what to do with all this splendor.

Actually at this stage in his life, he’s incapable of any voluntary motion. I think it’s only by five months they gain such advanced abilities as control of where they’re looking.

Babies are weird.

As he grows, he will see many illusions. He will watch paintings come to life as music plays for him, and he’ll see his father’s houses spin, and he’ll dive into schools of guppies and great whites in the swimming pool. But I don’t suppose he will ever know the ocean lapping up around his ankles, or will ever cast a fishing line, or have a house of his own.

There’s really no reason why he couldn’t. The rapist is allowed out all he wants. Even if we assume that Cecily won’t be because everyone is a controlling asshole who hates women, the kid can still go to the beach since it’s a boy.

Cecily then complains she wants a real piano, not the fake kind that makes holograms. Jenna says real things aren’t allowed here. No one considers that they could just ask someone for a real piano, just like it’s been almost a year and Rhine still can’t figure out she could just ask for the damn candy if she wants it so much.