A/N: So...there was a good response to the original fic both here and on AO3. I had a few requests for a sequel. I really enjoyed writing it and people seemed to enjoy reading it, so I saw no reason to stop. Cross posting this here from AO3.

Customary disclaimer: This is written for fun, not for profit. I claim no ownership of the recognisable characters.

"Hello?"

"Dr Carter? It's…"

"Winchester. Yeah, I thought you might call. You run out of meds?"

"No. Well, yeah, but that's not why I'm calling."

"Oh?"

"Yeah, um…you remember that surgery you mentioned?"

Dean had never wanted to make that phonecall. He hadn't wanted to make it with Sam standing there, anger and fear and desperation painted plain on his face. He hadn't wanted to make it with Cas solemnly listening in, hearing Dean finally admit just how bad things had gotten and that he needed help.

"You said you weren't going to have surgery."

"I…I changed my mind."

"What happened?"

He didn't want to tell her what happened. He didn't even know how. I almost killed an innocent person and when my brother stopped me my heart was pounding so hard I thought it was going to give out. It was hard enough to even admit to himself. Harder still to say out loud with Sam standing there.

"I, uh…I…"

Carter took pity on him before he even had chance to try and answer. "Know what? It doesn't matter. But you're sure you want the surgery?"

"Yes."

"Alright. I can do that. Just give me a week to get all the stuff together."

"So, you want me to come up to Chicago next Tuesday?"

"No. I'm not there anymore. I move around a lot. I'll text you the new address."

And that was how he'd ended up in an underground parking garage in Denver, knocking at the door to a basement apartment and hoping he was in the right place. Sam and Cas hovered apprehensively a few paces behind.

Several seconds pass in silence before Dean raps anxiously on the door again, but all it earns him is a glare for his impatience as the door swings open a heartbeat later. Carter gives him a cold look, not even greeting him as she casts a glance over his shoulder. "Who are they?"

"Oh, uh… that's my brother, Sam. And Cas. He's my friend."

"Hmm." She narrows her eyes. "They can wait out here." She gives a sharp jerk of her head to invite him in, but Sam protests before Dean even has chance.

"We're coming inside." His tone is firm. Almost intimidating, if Carter didn't just respond with a derisive smirk.

"This isn't a hospital. I don't have a relatives' room. There's a 24 hour café down the street, if you want somewhere to wait." She seems impatient to get Dean inside, holding the door open and shooting him a glare, but he stands stoically where he is.

"I'm having major surgery, here. You told me I wouldn't be able to drive for at least a month."

"I meant have someone pick you up in a week." Her face is still scowling in annoyance, but she seems to realise he's not about to come in unless Sam and Cas do too.

"Are you fucking serious?"

They both exchange a glare for a few seconds, but then Carter rolls her eyes. "Alright, fine. They can come in for the pre-op stuff, but I want them out after."

For now, Dean will take that. He hoists his duffel bag onto his shoulder and steps inside, Sam and Cas close behind. Carter's wearing a black tank top this time, the puncture marks on the inside of her arm still noticeable, although there's no angry bruise. Still, Dean's sure Cas and Sam must have noticed, and it makes him nervous. He's also noticing for the first time the blotchy ring of white, uneven scar tissue around her upper arm, like a burn, and it's raising even more questions.

Sam and Cas cast a suspicious glance around the new apartment at the same time as Dean. It's no cozier than Chicago; if anything even gloomier due to the lack of windows, and the walls are all granite blocks painted in faded-looking black gloss. The floor comprises black and white vinyl tiles that seem to have barely survived from the 80s. There are at least actual walls with doors this time, but the first area the entrance leads into is rather small combined kitchen and living space.

Carter waves in the direction of a couple of battered leather sofas for them to sit. Cas instead chooses to stand, arms crossed haughtily as he narrows his eyes at Carter. "So you're the demon doctor?"

"Yeah. And who are you? His accountant?"

"I'm an Angel of the Lord."

She just sneers. "That would be a little more impressive, were I Christian. Now you gonna sit, or not?"

Cas still hesitates, but with a look from Dean, perches himself awkwardly on one of the couches beside Sam. Carter sits herself down comfortably opposite Dean, reaching for the folder she's left lying on the coffee table between them. "Alright, so… I didn't send you any pre-op literature, but there's some generic stuff there I swiped from the hospital if you're interested. I got your bed prepped. How long of a stay did you pack for?"

"Just a week, like you suggested. Is that still okay?"

"For you, yeah." He notices she's not looking at either Sam or Cas. "I need to do a pre-op assessment before we go any further. I've got the room set up that way, if you want to come through?"

Dean glances round nervously, again taken aback by how quickly things are moving. Cas and Sam are both still looking apprehensive. "Why don't you tell us more about what you're going to do to him first?" Sam demands of her, but she just shrugs.

"You're not my patients. If Dean wants you to know, he can tell you."

"Look…" Dean can see the situation elevating quickly if he doesn't say something. He doesn't know why she's being so damn hostile. "I want them here. They're family. Can't you at least let them see what's going on?"

For a moment she purses her lips, turning her glare on him, but then just sighs as she decides it isn't worth it. "Alright. Fine. You all coming through, then?"

It seems to take Sam and Cas by surprise too, but there's no further protest as she leads them into the room set up for surgery. Dean dumps his stuff down by the sofas and follows.

As they enter, Dean recognises the familiar black vinyl exam table taking pride of place in the center of the room, and some of the other equipment also appears to have made its way here from Chicago. There's definitely a few machines and instruments he hasn't seen before.

"A power drill?" he hears Sam remark, his tone the exact mix or horror and apprehension that it's just triggered in Dean, and he's glad he didn't spot the device first.

Carter just gives a huff, not even glancing in his direction. "It's for trepanning. I work with what I have."

"Trepanning?"

"You fit it to a device on someone's head so you can drill a hole just far enough to…" She trails off, looking annoyed. "Why I am I even explaining this to you? It's not relevant."

Sam doesn't seem keen to pursue the question as she goes to retrieve a cart stacked with monitors and equipment, waving in the general direction of the table. "You know the drill."

Dean does, but he's quickly realising having Sam and Cas here does actually feel somewhat awkward. He strips off his jacket and shirt and then sits down as he waits for her to cross back over. He notices Sam is watching Carter suspiciously, while Cas is more concerned with watching him.

"You two can stand there like lemons, or you can…actually, I don't know what the fuck you can do," she shoots at the pair of them as she snaps on a pair of gloves and slings a stethoscope around her neck. She turns her back on them both as her attention turns to Dean. "Alright, I just need to see how things have progressed since last time. Shouldn't take long."

She starts with his blood pressure, working efficiently as she fastens the cuff around his bicep and inflates it. The only indication of the results is her slight scowl as she unwraps it again. "I'd ask if you watch your cholesterol, but somehow I don't think that's the root of the problem."

He bites his lip. "Not good?"

"I doubt you'd be here if it was."

Most of the tests from last time get skipped as she moves straight to pressing the stethoscope to his chest. His hisses from the cold, wishing she'd offer to turn the heating up again, but she does no such thing.

"Yeah, that definitely sounds worse," she remarks after a few moments listening, moving the diaphragm around to different spots on his chest. Hardly the most encouraging thing to hear.

"Don't sugar coat it," he retorts, but she just shrugs.

"That was sugar coated. The murmur's got really harsh and your resting rate's in triple figures. Definite irregularities, too. I need to get a closer look." She turns back to the equipment tray, and he keeps his eyes locked on her hands as she fills up a syringe. He knows what's coming.

There's a somewhat condescending, almost mocking fake smile on her face when she turns back to him. "Now this is some contrast agent. I need to inject it so I can see your heart better on the ultrasound. Don't lose your shit or anything."

He clenches his jaw wordlessly, knowing he earned that, but Sam interrupts as she starts slapping his arm to help find a vein. "What are you giving him?"

She doesn't even glance back over her shoulder at him. "Contrast agent, L'Oréal. Your ears not work?"

"What's in the contrast agent?"

Only Dean sees the roll of her eyes. "It's agitated saline. Completely harmless, I promise. Hospitals use it all the time." Then she plunges the needle into a vein.

Dean grimaces, but he wasn't unprepared as the needle slides out again. "Alright. Lie down," she instructs, although Dean can still see Sam watching cautiously over her shoulder. He does as he's told, trying to get comfortable as she brings the ultrasound machine closer. The screen flickers to life when she hits the power, although its display remains blank. "This is probably gonna feel cold…" That's the only warning he gets when she starts smearing the ultrasound gel on his chest and positions the wand. His sharp intake of breath belies that yes, it's cold. Like she's been storing it in the fridge.

Grainy images flicker across the screen and he hears the rapid whoosh-whoosh of his heartbeat, something he'd only half expected from the limited medical knowledge he's gained from Dr Sexy, MD. He has some idea of how the device is supposed to work, but most of the quivering shapes on the display are meaningless to him. Instead, he watches Carter's face. Despite her usually perfect look of apathy, even she's struggling to keep her expression blank. "Yeah, that's…" He doesn't like the way she's biting her lip. "That valve's completely fucked." The wand slides lower, closer to his sternum. "And the right side of your heart is just…not doing what it's supposed to. At all." She doesn't point out anything specific, but he can see the rapidity with which the on-screen shapes are fluttering. "Honestly, I don't even know how it's beating like that and you still managed to walk in here upright." She slides the wand right again, and down, scrutinising the display for a few more moments. "Right. That scar tissue there has to go." Her hand waves vaguely over the bottom left of the screen, but Dean thinks he can see the cluster of white she's referring to. His mouth goes dry and he swallows nervously. On the screen, he thinks he sees the disruption to the pulsating rhythm as his heart gives a skip.

"Right…" She removes the wand from his skin and straightens up, throwing a few tissues at him to clean away the gel. He scowls slightly, but starts trying to wipe the jello-ish substance off his chest. Meanwhile, Carter at last turns her attention to Sam and Cas with a cold glare. "Based on that, I'm happy to proceed with the surgery immediately. But you two need to go."