The topic of Delta was a delicate one. That was something both Tenebaum and Sinclair were acutely aware of. But given the topic of their recently evicted conman was even more volatile, they spoke about the big daddy instead.

"Ignoring the spectacular failure of the original plan, what can we do now?" Sinclair asked. He'd been watching Tenebaum pouring over her notebooks. Some older than this train and others fresh from the day. When their lives were not in immediate danger she was writing, and if not that then reading through the old collection of books she managed to keep with them.

"Define," Tenebaum replied stiffly, clearly her tolerance for him was now quite low as well but Sinclair wasn't going to explain himself to her, again.

"My meaning, doctor," Sinclair elaborated in a painstaking slow drawl, "Is that we have an escape pod we can't move without Lamb's key, a child soldier for a missing daughter and a soldier of our own that could lose his mind any time in the next four hours. Not quite a hand dealt in our favour, now is it?"

"Of these things, which is it you are most concerned over?" Tenebaum shot back, finally looking up from her hastily scribbled notes to fix him with one of those dead eyed looks of hers that made Augustus squirm in place. He didn't like people looking through him like that.

"The part where we all die."

It was a dodge and they both knew it. Sinclair didn't bother to correct himself as he glanced towards the little cart at the end of the train that Delta had vanished into some time ago.

If they lost Delta they didn't have anything to work with on the ground. He was no fighter and Tenebaum, while steely as anything, couldn't take on all of Rapture the same way the alpha series could.

It was something of a closed loop of misfortune.

They needed to get out of here and they couldn't without Lamb's key.

They couldn't hope to get Lamb's key without Delta, and they couldn't keep Delta from losing his mind without Eleanor.

Eleanor was thoroughly mind controlled with Lamb's influence.

So they needed to get to Lamb, and for that they needed Delta, and they couldn't keep Delta from losing his-

Rinse and repeat.

For every step they needed to take they were missing a piece to another step that couldn't be taken without another. The round about nature of it all made Sinclair's head hurt and a spiteful little part of him couldn't help but somehow find Atl- Fontaine to be at fault for this.

And through all the head and heart aches, Sinclair had become suspicious of Tenebaum once more.

"You knew, didn't you doc? About Eleanor and Lamb," he asked finally, voice cold.

Tenebaum failed to even flinch at the casual accusations he leveled her way.

"Big Sister had few candidates. Eleanor was the most suitable conclusion," she confirmed in that dry, guiltless way of hers that Sinclair took exception to.

"That so? Well that's a mighty clever of you doc, but why don't you fill me in on the part in these conclusions of yours where the kid actually didn't lose his mind."

Sinclair's teeth were grinding together as he watched the calm woman turn the page to her notes. Whatever she was looking for in there he doubted it was their get out of jail free card and finally Tenebaum's composure caused Sinclair to lose his own.

"You never had a plan for that did you? You didn't even think getting Delta to Eleanor would save him did you?"

"It stood to reason that if we could reach the Big Sister we would reach Lamb, and-"

"That doesn't answer my fucking question, Brigid!"

Sinclair shouted and for a beat they both went quiet. Tenenbaum in her silent consideration and Sinclair in his seething anger.

Finally she closed the notebook and did not look at Sinclair when she spoke again. Quiet now but never apologetic, unwilling to give him a sense of moral high ground no doubt.

"There was a small chance she would stabilize Delta. But… no. I never believed the Big Sister would cure Delta."

Sinclair drew in a breath, fists clenched by his sides as he prepared to shout the callous woman down for her repeated twisting of the truth. Ignoring how truly hypocritical it would be to accuse her of using Delta when he'd always been so upfront about his intentions to do the same.

Tenebaum didn't let him get to his furious rant, instead cutting it off in its infancy by continuing quietly, "The alpha series were always unstable. Experimental. Unsustainable. The prototypes more so than their successors. Their stabilization relied upon two factors."

It may have been the clinical way Tenenbaum held her little lecture that kept Sinclair silent as he raised a finger for each of those factors.

"First, a little one. Nearby and well. Connected and secure. For us - Eleanor. A necessity." One finger was then lifted.

"Second, ADAM. A purified, highly concentrated variation of the substance. Most big daddies sustain on raw ADAM produced by the little ones. Prototypes are unsustainable on concentrated ADAM and it goes bad when they do. Rare, hard to produce. A drain on production."

Sinclair resisted the urge to roll his eyes, figuring that 'drain on production' came directly from their days being in the business of business. Discarding models that were not fuel efficient.

"Okay, so the chief has a refined palate," Sinclair snarked, "Doesn't he get that from Eleanor? Isn't that the whole point of their bonding?"

"For a big daddy not once dead, yes. Delta is no such big daddy."

Tenebaum had the strangest way of being patient in her teaching while appearing thoroughly impatient with her dense student. Regardless she tried again to impart this crucial second factor onto Sinclair.

"Delta needs this concentrated ADAM directly from a stable carrier."

She could see the remark brewing in SInclair's eyes and cut off his suggestion before he could make it.

"Not from a little one. Little Sisters produce raw ADAM. Cleansed and ready for reuse. Not concentrated ADAM. That can only be manufactured."

If it could only be manufactured, then they were up shits creek without a paddle. There weren't any sane people running ADAM production left and the entirety of Rapture's ADAM supplies were in Lamb's hands to begin with. They could hardly go around playing chemist, even with Tenebaum's expertise, Sinclair knew that much.

"So you took all this time just to tell me how screwed the kid is? You could have done without the lecture for that-"

"Herr Augustus," Tenebaum hissed sharply, pushing him back into silence as she clarified. "Concentrated ADAM can be manufactured, or stored by an uncompromised carrier. Prototypes, like our Delta, use the same strain of ADAM, and can be harvested. Provided the ADAM has not gone bad with their minds."

"There are no prototypes like Delta," Sinclair argued hotly. "Sure there's maybe a couple of alpha series locked up back in Alexander's old coop. But even if we could get back there safely, we don't have the time before Delta goes cooky. And hell! According to you they wouldn't even do it, stability and all that nonsense. I don't think there's any calm alpha series still running around the place."

"Not 'alpha series', Herr Sinclair. Prototype." The second finger was raised finally. "Any prototype."

And Sinclair understood. He understood with the sensation of his stomach dropping out from under him. There was still one more prototype running around Rapture, one they'd had the misfortune of encountering not all that long ago. Certainly closer to them than any alpha series, one that could be reached in time.

"... Brigid…" Sinclair began but couldn't find the words, hands held out from his sides in an expression of something bordering desperation. "You can't… the kid can't… God, that thing would destroy him. Even if it didn't kill him, it would kill him."

And Tenebaum clearly knew that, but her expression remained dark, unyielding. "A mercy killing," she reminded him in a stone cold murmur, leaving Sinclair all but gutted.

Then she turned away from him and back to her notes.

"I will not tell Delta what he must do, but we know what must be done. You have not shied away from such things in the past, perhaps it is best you express this trait to Delta."

The only indication that Tenebaum felt anything at all for the terrible thing they would be asking of Delta was the small hesitation in her voice before she finished quietly.

"It falls to Delta to make the choice. I have no doubt of his decision but… well, perhaps it would do him some good to have a steady hand by his side at the end, Augustus."

Sinclair almost reminded her that he was hardly in a position to offer support of all things to Delta. How could she expect him to provide a steady hand when those same hands had directly given Johnny and Walter over to Delta and Demo.

After a second spent swallowing around the guilty lump in his throat Sinclair nodded stiffly. "It's pretty underhanded of you not to tell us this earlier doc...but I'd be a rotten liar to say I didn't understand it." They'd gotten this far and Tenebaum must have known that they couldn't very well back out now. No matter how ugly the fight got. Not when they were so close to the end.

"Just tell it to me straight now, Brigid. Does he get to walk away from this? In the crazy hypothetical where he guts Demo and gets Eleanor back, will it really be enough?"

Again Tenebaum paused and Sinclair couldn't have told anyone if she was weighing their odds or simply deciding if she ought to lie.

Finally she glanced his way with a tired, drawn smile. "Yes. I believe so. Long enough to feel the sun again. As he deserves."

Sinclair did not have the strength to ask if she thought he'd live long enough to enjoy that feeling in full as well, instead taking the small shred she gave him with a tired sigh. Reaching for his dwindling pack of cigars to help ease his nerves.

"Guess I'll be telling the kid what the plan is, huh?"

Tenebaum didn't answer him outside of opening up another notebook and comparing something in the writings to the first. Yeah, typical.

Served him right he supposed.

Without another word Sinclair went in search of Delta, not entirely sure how he'd be breaking this particular news to him.

Demo was a beast in its own right and their few encounters with it had not ended well for Delta, physically or emotionally it appeared. He'd lost the plot on both encounters, nearly costing his life the second time. Demo and Delta were hardly an even match and Sinclair knew that had he been placing bets on the fight, he'd be unable to bet on the horse he wanted to win.

Even if Demo didn't kill Delta in the fight, a victory was unlikely to be taken all that much better. But what choice did they have now?

As Sinclair stepped into the tiny cart at the end of the train he was alarmed to find the door not properly latched. A small unpleasant sensation rushed through him as he wondered if he might not actually have to tell Delta anything at all, he was sure they could be heard with the door open.

Looking up he spotted Delta in an instant and that dreadful feeling in the pit of his stomach only grew worse.

Delta was waiting there for him.

...and he was sat in front of Louis's painting.

Topside.

Sinclair took in a deep breath. If it was to steady his racing thoughts or simply to remind himself to keep pulling fresh air into his lungs was anyone's best guest. But, regardless, it helped. At least Sinclair had to tell himself it helped and that his fingers weren't trembling just to keep a level head.

"Hey, Chief," Sinclair greeted cheerily, the sheer forced brightness of it almost caused Augustus to wince himself, he toned it down as he went on. "How are you holding up?"

Delta answered him as best he could.

A little shrug accompanied by a turn of his helmet to assure Sinclair he was listening and acknowledging him. Heaven forbid he come across as aloof or discourteous. But they both knew that he must have heard it all.

Distantly, Sinclair recalled that Johnny had once been quite the conversationalist. Not because he had anything particularly profound to say, simply that he had a lot of terribly mundane little things he felt he had to give voice to.

Sinclair wondered now if Delta would speak just as freely as Johnny once had if he still had the voice with which to do so. Somehow, he doubted it. Rapture took the best from everyone, even something like words from a chatterbox.

For a short time it even took the words from Sinclair as he watched Delta sitting by the painting. Did he remember everything? That couldn't be it, their one sided conversations were still too passive for Delta to remember his face from their history together.

Yet, it was clear he remembered enough to know this painting belonged to him.

With another equally helpful deep breath Sinclair stepped into the little end cart with Delta, thinking the space was too cramped for the oversized kid. Once they were on the surface he'd have more freedom to roam, in theory. If he ever got back to his namesake.

"Sitting with the blues, huh sport?" Sinclair suggested as he came to sit cross legged next to the silent lad. Another shrug, and this time his gaze slipped back to the painting.

Sinclair tried feebly to keep Delta's attention on him. "Maybe we ought to get you some paints. A picture speaks a thousand words and all that, so they say. Might get you communicating again. Make an artist out of you."

Delta might have been laughing, at least he hoped so. The little tremors of the big daddy's shoulders could just as easily have been silent sobs and Sinclair couldn't bring himself to pretend he didn't know that.

After a beat of silence, Sinclair decided to adopt Delta's new method of communication and didn't utter another word as he pressed a hand against the boy's back. Waiting for the laughter or sobbing to ease.

They didn't speak again after that. Not for quite some time.

Sinclair had always hated the quiet and hated the inability to speak even more so.

Words were the weapon of choice in Rapture for the longest time after all and longer still for himself personally. Being rendered mute left him defenceless in a way that was unsettling for him. But he stayed quiet now, keeping with Delta's way of communicating as the quiet man leant into the hand pressed to his back.

Surprisingly Sinclair didn't mind the quiet so much this time.