A/N: The following chapter is shorter than I wanted it to be but it serves its purpose. There's no Eris interaction in this chapter, no Eric at all. But I wanted to pick up from the last chapter and introduce another familiar character. I hope you enjoy.

Tris smiles at her brother as she walks into the lab in Erudite. He's sitting in a swivel chair and his expression is pleasant but he doesn't quite smile back. As he stands from his seat, he tells his supervisor that he's taking a quick break and that he'll be back.

"Long time." He finally says to her, approaching where she stands in the doorway.

"Yeah." She breathes out, accepting the awkward side hug he gives her. "What are you all working on in here?" She asks, looking around the room. The lab is clean, the white counters are organized and the lab coats all the researches are wearing are starkly white over their blue shirts.

They both know all she has to do is log into her computer and check the logs, but she won't.

"Just the normal stuff." Caleb responds nondescriptly. He gives her an easy smile — one for her benefit more than for his. "Mind if we stop by the recreational room before we head out to the courtyard?"

"No, not at all." Tris shakes her head. She gives a wave to the few of Caleb's coworkers that notice them.

She regards her brother with a pleasant, though a tight lipped smile — one he's used to— as they enter the hallway. There are fewer people in the building, and even fewer young people when compared to other factions. The last few classes of initiates have returned to their homes, either to their parents or with friends. But the faction itself is one on the outs. The research they do, and the teaching in schools they do is important but there's a stigma left behind — it almost feels like an omen — from Jeanine and her team's body of work. Tris herself doesn't really understand what gratification Caleb gets out of staying. But then again, there's nothing for either of them to go back to in Abnegation. Their mother and father are dead. And what they died for — to save her — goes unmentioned.

Their relationship took a wide turn after they'd chosen two different factions. And the damage he'd done during the craziness, she thought would be irreparable. But he was still her brother. And with both their parents dead, gone and never to return, he was all she had. He is all she has.

He collects his lunch, and offers her a bottle of carbonated water. She nods and takes it from him as they exit the small kitchen in the rec center.

She's allowed herself to look around the place as they exit to the front of the Erudite building. So many lives had been lost around there, bodies littered around the streets, Dauntless, Erudite. She remembers them — maybe not who they were or what they were like as individuals, but she remembers collecting them — and her stomach lurches each time. She also remembers what she'd been subjected to while Jeanine kept her there. A sour taste fills her mouth, as if she's going to vomit, but she squares her shoulders. Her fingers itch to grab the gun in the waistband of her pants — a reminder that it is indeed there, and she wouldn't be able to pull the trigger if by some not-so-unbelievable stretch of the imagination she'd need to use it.

She sees Will's face. And again, her body threatens a reaction.

If her sibling across from her notices her inner battle, he doesn't show it. And she knows that he does see it. There's no way he doesn't. But he's never been one to put her on the spot — their history, however dark and convoluted in she past couple years, does nothing to make her believe he doesn't know her. "So what's up?" Caleb asks when they settle at a white painted picnic table. He unfolds his lunch, a simple sandwich he undoubtedly threw together at the last minute. Natalie would have been mortified. Tris places her chin on her fist, lifting her shoulder to shrug at him. "You didn't schlep all the way over here for nothing did you?"

"The train ride isn't that long." Tris retorts, her eyes twinkling with sass. Her brother rolls his eyes and flicks his thumb at the corner of his mouth to clean it off, sticking his finger in his mouth to lick whatever it was away. She laughs. He could be such a boy. They were forced to grow up so quickly in their city. And with the terrors they've experienced or played a part in, she's glad he's relaxed into this new life.

"You look tired, Bumble Bea." Caleb says it so casually — the childhood nickname he'd call her when no one else was paying attention — and a wave of sadness and nostalgia wipes over her. "Sorry." He leans over his lunch, hoping she doesn't bite his head off.

Tris feels tears prick the corners of her eyes. She presses the heels of her palms in her eyes. She thinks back to her life before her choosing ceremony; before she was divergent, when she was just a moody teenage girl just trying to fit in. So much has changed in just a couple years. And she can't remember when or why it was suddenly so different. She hates feeling that way and wants everything to be simple.

"You haven't called me that in… years." She finally responds, stopping him mid bite into his lunch.

"You'd hit me with the nearest, softest pillow every time I said it." Caleb recalls with a reminiscent chuckle.

"I was too kind to you Caleb Prior."

He's silent for a few moments, feeling regret pool in his belly as he remembers some of the strain he's caused on their familial bond, the way he'd sold her and others up the river out of fear. "You still are… too kind to me."

She settles her hand over his, "You've made your mistakes." Tris knows he still beats himself up over what he'd played a part in, telling Jeanine anything about his sister, telling the woman where Tris had been hiding out in Amity. But what's done is done. "We're family. You're all I have left Big Brother."

Part of her is sad that that is true. That he's all she has left in this godforsaken life. That shouldn't be the truth of it. But it is. It's just the two of them. If push comes to shove, she'd make sure he made it out. No matter what's been done, she can't hold a grudge. It's not what her parents would want. She wakes up in the morning, puts one foot in front of the other, because her parents didn't sacrifice their lives just so she could throw hers away.

"I am tired." Tris admits. Her smile is sad and he regards her with the same smile.

"Not warming to your new position?" He asks. Everyone knows she's on the new ruling committee. She's fought it tooth and nail so far. And yet…

"I don't want to." She admits a moment later. And really, it's not the look that he gives her that makes her recoil. It's that she knows that she sounds like a brat. But she can't possibly be effective as a leader if she has no desire to be one.

"Why?"

"What have I done to earn it?" She asks rhetorically. "All I did was survive like everyone else."

"You fought." Caleb is relentless, he won't let her pity herself. He knew how little self pity helped "You saved lives."

"I took them too."

"That wasn't your fault." He sets his lunch aside and rubs his fingers into a napkin. "We've all done things we're not proud of. You can't run away from it. So take the time you have now to make a difference." That's all he's ever really wanted. To feel like he's done something important. That desire had been manipulated and he's not proud of that but all he can do now is continue to try and reach his goal.

Tris presses her hands to her face and exhales. As she looks back up, she smiles at him for his effort to make her feel better.

And then she remembers why she was there in the first place. The time she spent in the factionless sector grates on her nerves and she's still uneasy. "Caleb."

"What?" He asks with a mouthful of food. His brow quirks at the way her expression doesn't change from the stony determination she's put on. "What's wrong?"

"Theoretically… if someone wanted to wipe out an entire faction, could it be done by infecting them with a sickness?"

"It's possible." Caleb nodded wearily. He folded his hands over his chest. "But everyone save for children who are too young, have been vaccinated for illnesses that would pose that kind of deadly threat."

"And if someone decided to make their own, or weaponize… like, the flu or something." She didn't know what it could possibly be, but the thought of someone spreading disease to get rid of a certain group made her uneasy. Another battle between them all wasn't needed.

Caleb hummed, "It's possible." He didn't want to sound like a broken record. But he didn't want to lie either. It wasn't out of the realm of reality — erudite it self had the means to spread that kind of attack. "That person would have to have access to a lab, and have the means to travel undetected between here and wherever it was being spread." He shook his head, pausing. "Wait…why are you asking me this?"

"I said theoretically." Tris responds. She knows it's a lame one at that but Calen relents. "It can be done though?"

"Yes."