So this is my take on what may have happened to Four after Tris left. I was thinking of writing what he was up to while she was there but I am just going to skip forward when Four decides to go save her.

Four slowly began to wake up and reached his arm out to pull Tris back into him. It hit mattress. His eyes flew open and saw her side of the bed was empty and felt cold. His heart dropped but he quickly stopped himself. She had promised, she would not have left like that, she was probably just in the cafeteria or something.

Four quickly got dressed and ran down to the cafeteria, scanning the tables for that telltale blonde head. Nothing. Then he saw Christina and figured she had to know where she was. As he approached Christina, he saw her staring at the table but not eating her food.

"Christina?" Four moved to sit next to her. Something wasn't right, something in her eyes worried him. "Have you seen Tris? This morning when I woke up, she was gone from my room. Did she come back to the dorms last night or this morning?" The hope in his voice was killing him, he was barely holding onto it and just needed Christina to say the right words.

"Didn't she tell you? She was going to visit her brother in Abnegation. She came and found me this morning to tell me that and that Marcus knows why Erudite attacked and we had to find out."

Four stopped breathing. She had lied to him, comforted him, kissed him and then left. She manipulated him just as his father would to get what she wanted out of him. This one act confirmed to him that he loved her more than she loved him, if she even did at all.

At first he felt numb, but now he felt an anger rise up in him that had never been there before and Christina was the only one around to receive that anger.

"WHAT!? And you just thought you would let Tris go running off to Abnegation while we are at war, when someone wants her dead? What were you thinking? How could you?" He grabbed a bowl on the table and threw it across the room but it didn't make him feel better, be wanted to punch things and shoot things until all of these emotions left his body. Christina looked terrified and then became angry herself.

"Why is it my responsibility to keep her here? Maybe if you weren't acting like such an asshole these past few weeks she would have stayed. You are too worried about becoming a leader than the relationship you fought so hard for during initiation!" Christina was tall and almost came up to his height as she was screaming in his face.

"Do you even understand what has happened? Tris didn't go to Abnegation, she just went to turn herself in to Erudite. I was protecting her from herself, she can't help but sacrifice herself after everything she's been through. You should have stopped her, made her see reason, but no now she's probably dead already!"

The yelling was drawing a crowd and Zeke came rushing in and pushed the two apart. He turned to Four, "What is the matter with you? People should not see a leader reacting this way! What has gotten into you?"

Four turned to Zeke, a new victim for his anger when it should be directed at Tris. "Well Tris felt the need to go sacrifice herself and Christina here just let her walk on out of the compound." Zeke turned to check with Christina and when she nodded her head that was all Four needed, the verification that Tris had indeed left to sacrifice herself without even a thought toward Four's well-being. He turned and ran, sprinted out of the cafeteria.

"Four!" Zeke shouted after him but he had to get out of there. He was going to head to the chasm, where he used to clear his head, but that was their place now and he couldn't be around where memories of her were.

Instead he found himself a nice dark corner of the practice room to sit in and wallow in his thoughts. He had laid it all out on the line for Tris last night, he would not survive without her. She was a part of him he couldn't live without like his lung or heart. For her to completely blow that off and leave, to sacrifice herself for others, it showed that her love to him was so insignificant it didn't matter to her. If the roles were reversed and she asked him to stay for him, he wouldn't have given it any second thought, he would have stayed. Eventually Four slipped into a light sleep and his mind relaxed, pouring through all the great memories they had.

Four awoke to the sound of the door opening, for a brief minute he thought it was Tris but realized he may never see her again. That was when the tears started; at the thought of never seeing the girl who changed him again. He buried his face in his hands as Zeke sat down beside him, staying silent. After a few minutes, Four pulled himself together and turned to the best friend he has had since he transferred.

"How are you man?" Zeke asked, "For real, not that fake answer everyone usually gives."

Four laughs because he was ready to give that answer. Maybe it would be good to talk about this, even thought it wasn't something he was used to with anyone besides Tris. There was that knife again, would it cut every time he thought her name?

"I feel so betrayed. Last night she promised me she wouldn't leave and then waited for me to fall asleep and left the first chance she got. What does that say about our relationship?" Four asked Zeke.

Zeke just took a deep breath, "Well haven't you said it's been bad since the war, you've been fighting a lot? Maybe you guys aren't supposed to be together, it might not work out."

Four almost hit him, "No, she is who I'm supposed to be with! If this stupid war hadn't happened she would be siting here next to me right now. What was she thinking? I keep thinking she will come walking through that door but for all we know she is already dead." Tears welled up in his eyes again and he let them silently fall down his cheeks. He realized how emotional he was being in front of Zeke right now but either he didn't care or understood.

"She's still alive, she has to be. Jeanine has been itching to get her hands on one of you for so long, she isn't going to waste this opportunity." Zeke pointed out which made Four feel worse.

"Thank for pointing out she is probably being tortured right now, that helps," Four said, feeling anger rise up in him again.

"Whoa man, calm down. All I meant was we have a chance to save her. We need to come up with a plan and get her out of there. Even if it's you and me, if she means as much to you as I think she does, we'll go in and get her."

Four shook his head in agreement, leave it to Zeke to see things with a clear head. But then he realized something, "What if she doesn't want me to save her? What if she doesn't feel the same way about me anymore?"

"C'mon, you are Four, Dauntless badass. No girl can resist you, just brood a little bit and she will come running back to you. That's your problem, you've been smiling too much, your face looks weird when you smile." Four reached out and took a playful swing at Zeke, leave it to him to lighten the mood.

"Let's go, everyone is worried about you and you owe Christina an apology." Four got up and followed Zeke out of the room, but not before giving him a smack on the head.

"Alright let's go plan a rescue mission, I need my girl back so I can stop smiling at her." They both laughed as they walked out of the room; Four's laugh a little empty at the space beside him that was usually filled with Tris. He would get her back and show her once and for all that they belonged together.