I raise the knife to shoulder height, keeping my eyes on his neck, right where I could cut the carotid artery. Before I can move, the front door opens. Even though no one in Abnegation locks their doors, everyone knocks first out of consideration. But whoever's there not only doesn't knock, they throw the door open so fast the knob bangs into the wall. The sound startles me. I look to see who's there.

For a moment, I hardly recognize Caleb. If I didn't know him, I'd never guess he was raised Abnegation. He's truly Dauntless, dressed in a black t-shirt and jeans. His shoulders are broader than I remember, and the muscles in his biceps are prominent. There's a ring at the side of his eyebrow in addition to the two through his earlobe. A tattoo wraps around one wrist. But his hair is still Abnegation short, and when his eyes widen at the sight of the knife in my hand, they're still the same hazel as our mother's.

"What the fuck are you doing?" he says to me, surprised. "Get over here." He marches into the living room and shoves me behind him with such speed that I can't even process what's happened until I'm looking at Marcus over his shoulder. Marcus stops his pursuit of me when he sees Caleb.

"Caleb?" Marcus says in disbelief. Then he scowls. "You have no right to be here."

"And you," replies Caleb in a calm, even tone, "had no right to do what you did to me and Tobias." He reaches underneath the back of his shirt and pulls a gun from his waistband, aiming it at Marcus. "Hands where I can see them," he orders. Marcus raises them slowly, like he's unsure if Caleb means it. Caleb keeps his voice low and says, "Tobias, I have another gun in my boot. Reach down and take it."

"You need to get out of my house," Marcus says. He sounds like he thinks he has control of this situation. I'm not sure if he's acting brave or if he believes he still has any sway over Caleb. It's clear to anyone with eyes that Caleb is fully his own person. No one has sway over him anymore. I kneel and gently lift the hem of his jeans. The gun at his ankle just about fits in my palm, and it's surprisingly light. I thought something capable of taking a life would be heavy with its potential. "At least you were smart enough to recognize you didn't belong here, you weak, selfish—"

"Shut up!" Caleb yells. Marcus looks almost as stunned as I am at Caleb's outburst. "I'll get out of your house soon enough, and Tobias is coming with me. He's going to go upstairs and get whatever he wants to take with him. You're going to stay right where you are. If you stay silent and don't move, I'll let you live. It's more than you deserve."

Marcus tightens his jaw. "If you kill me, that's not just a mark on you. It's a mark on Dauntless. You'll be a murderer, bring down the entire faction."

Hearing those words, that Caleb is the one who could damage his faction, ignites that same raging spark I felt when Marcus told Caleb he was selfish for letting me take his punishment. I match Caleb's position so that both of us are aiming our guns at Marcus. He has always put faction before blood in the cruelest ways. My selfish nature has always been his excuse for what he's done to me. Now it is my weapon to use against him. "Then Abnegation comes down with it," I say. I hate having to say it, hate having to threaten an entire faction of people who strive to make our city a better place. But it's the only way to get through to Marcus.

"Go get your things," Caleb orders me, tilting his head in the direction of the stairs. His gun doesn't move an inch. "Try to follow him and I'll shoot you," he says to Marcus.

I tuck the gun under the back of my shirt just like Caleb had his and run up the stairs, pleased at his confidence. Dauntless has been good for him. More than physical strength, it's given him mental strength. I'm jealous of him, then irritated at myself for it. Jealousy has no place in a selfless life. But I don't have time to think about that now. In my room, I throw socks and underwear and a spare shirt into my old school bag. There's a stack of gardening books on my desk, and I smile when I see it. Some good did come of growing the extra food after all. I'm almost a little guilty about having destroyed the garden, but I have no use for it anymore. A back yard full of salted earth and one poisonous plant in a lone pot is exactly what Marcus should be left with.

Back downstairs, I look at Marcus for a minute as I join Caleb. I don't pull my gun immediately. Instead, I think about all the things I should say if I don't plan to see Marcus again. I should tell him that when he wakes up tomorrow in an empty house, with both his children gone and others in Abnegation wondering where I am, he will have no one but himself to blame. He won't be able to make excuses for long. The Abnegation may be focused outward, but if one of their own goes missing without reason or notice, that could make them ask questions.

I should tell him I forgive him. That even as much as I hate him for what he did to me, did to Caleb, I understand that darkness inside that drove him to it. Because I have it too. If I refuse to forgive him, it's like not being able to forgive myself.

Then I hear Caleb. "Are you ready?" he asks.

The entire reason he's here, wearing black, is Marcus. I decide I'd rather live without the closure, without ever knowing the truth about the curse I carry, than tell Marcus he was right about anything. "Yes."

"There's one more thing I want you to know," Caleb says to Marcus. He speaks quietly, but his stance is strong. "Tobias is a better person than I am. Every day from now on, you're going to wake up wishing you were half as selfless as he is. If he did this, he'd regret it. But I won't."

I'm about to ask Caleb what he means by "did this" when he shoots Marcus in the leg. The blast from the gun makes me jump. It might be the loudest thing I've ever heard. When my ears stop ringing, I turn to Caleb in shock.

"Did you…" Marcus is on the floor, holding his right thigh and howling in pain. "Is he going to die?" Caleb's bullet didn't land anywhere near Marcus's heart or his vital organs, but I don't know enough to tell when other kinds of bullet wounds might be fatal.

Shaking his head, he says, "Not immediately. He might if he doesn't get some help."

My instinct is to run to the neighbor's house and tell them to call for a medic. Erudite keeps a doctor at the Abnegation clinic around the clock. Caleb must read some of my intentions on my face, because he says, "No medic. I'll leave the door open. It's summer; people have their windows open. If someone hears him yelling, he'll get help. Now come on. A lot of people heard that shot."

Unable to argue with his logic, I follow Caleb down the front steps. As pleased as I am to hear that he thinks I'm a good person, I wonder if I could be as forgiving as he is, allowing Marcus the chance for someone to find him. I think about starting a fire, burning the house down around Marcus. But it's a perfectly good house, one that could shelter other people in Abnegation. Families. Normal ones. Marcus will wake up tomorrow morning and every morning after that with two empty bedrooms and no one at the table and know that he brought that loneliness on himself. I could stay and try just as hard to change Marcus as he did to change me, but it would all be for nothing. Neither of us has the power to make the other into what he truly wishes for the other. And I am not so selfish as to think I could.

Beyond Caleb, standing on the sidewalk, there's a Dauntless woman. She's about my age and short, with chin-length blonde hair. A tattoo of flying birds peeks out from under her collar. "Who is that?" I ask Caleb. She looks vaguely familiar. I think I might have seen her the day I went to Dauntless.

"That's Tris. She's my friend. She's here to help." He looks to her, then hesitates before he speaks again. "Come on. We need to be gone before someone finds Marcus. I'll explain things on the way."

We join Tris on the sidewalk. "Are you ready?" she asks both of us.

I can't imagine what she thinks I'll be ready for, but I nod. Wherever she's taking us, I'll go. Even if she plans to dump me in the factionless sector, I'd be okay. I can never, will never, go back to Abnegation. I look in the direction of Susan's house and almost ask Caleb if we can say goodbye to her. It would only take a minute. But that's a minute I don't have. Caleb is right. We need to get out of here fast. When we get to where we're going, I can write her a letter.

Tris starts to walk away, but Caleb lingers on the sidewalk for a moment, looking back at the house. When she realizes he's not following, she turns back and puts a hand on his shoulder. "Hey," she says softly, "are you sure you're all right?"

He swallows and nods. "Yeah." Then he lets out a quick breath. "Let's go."

The three of us walk for a few blocks, past a small park, and I realize we're headed in the direction of the train station. Caleb and Tris are fast, and it takes some effort for me to keep up. Once there's a full block between us and the edge of the Abnegation sector, we slow down.

"Hey, Tris," he says to her, "can you give us a minute?"

"Sure." She looks around, but there's no one anywhere. "I'll go ahead. Meet at the station?"

"Yes. Thanks." He gives her a small smile. Then he watches her walk away. When she's near the end of the block, he turns to me. "There's something I want you to know up front: Before we came here, I told Tris about Marcus," he tells me.

"What?" I am astonished by this reveal. I've built my life around protecting that secret, protecting an entire faction, and Caleb just went and told another Dauntless? "How? Did…" I look at Tris's back. "Did you tell anyone else?"

"No. And I hadn't…really meant to tell her in the first place," he admits.

That does nothing to answer my questions. Extrapolating from the little I know about Dauntless, I ask, "Did she beat it out of you?" I feel my protective instinct toward Caleb kick in. I still have the gun. If she did anything to hurt Caleb, I'll kill her myself. She won't be another Marcus.

"No!" Caleb's response is immediate. "I told you, she's my friend. We can trust her."

"How do you know?" The only person I've ever been able to trust is Caleb. Tris is a stranger to me, even if he vouches for her.

"It'll take me some time to explain. You're going to have to believe me for now. Can you do that?"

It's not like I have much of a choice. "Okay. Yes."

"I promise I'll tell you soon. Tonight. When we get where we're going." He is earnest. And in all fairness to him, he's never broken a promise to me.

Then, to my surprise, he hugs me. I stiffen and almost pull away out of instinct. He holds me tightly, though, and I let myself relax and hug him back. I hadn't realized until now that I was starved for the company of someone I loved. I hold him with all my strength, inhaling the scents of leather and laundry detergent.

"I'm sorry," he says as he lets me go. "I know I owe you an explanation, and you'll get one. I was so incredibly wrong about everything. I'm going to make this up to you."

Shaking my head, I reply, "You don't owe me anything."

He bites his lower lip. "If you still feel that way after tonight, then okay. For now, let's get to the train." When he starts walking again, I follow.

We have to be going to Dauntless. I think back to Visiting Day and realize the train isn't going to stop there today. "I'm going to have to jump off, right?" I ask Caleb.

"Yes." He sounds almost cheerful when he says it. "But I'll help."