Quote 4
I step to the side so I stand in front of the mirror. I see muscles that I couldn't see before in my arms, legs, and stomach. I pinch my side, where a layer of fat used to hint at curves to come. Nothing. Dauntless initiation has stolen whatever softness my body had. Is that good, or bad? (14.3)
Yet another mirror scene. Notice that Tris is still a little conflicted about this new identity thing. Now she recognizes this girl as her, but she's not sure that she likes the changes. Although, when you read this, did you have any confusion about whether you thought this was a good thing or not?
Quote 5
No, I was wrong; I didn't jump off the roof because I wanted to be like the Dauntless. I jumped off because I already was like them, and I wanted to show myself to them. I wanted to acknowledge a part of myself that Abnegation demanded that I hide. (21.11)
Tris here considers the idea that the Dauntless initiation didn't change her identity; it just allowed her to bring out a part of her identity that she had to hide before. She hasn't changed, she's just been given room to show her true identity. (But if you think this issue is settled, keep reading, because things are about to get confusing.)
Quote 6
Tori was the only one in the tattoo place, so I felt safe getting the symbol of Abnegation—a pair of hands, palms up as if to help someone stand, bounded by a circle—on my right shoulder. I know it was a risk, especially after all that's happened. But that symbol is a part of my identity, and it felt important to me that I wear it on my skin. (25.2)
Oh, geez, really? After all that "I'm Dauntless now, I always was," now Tris is back to saying "well, I'm a little Abnegation, too." Also, check out that her acceptance of her Abnegation identity comes in the form of… a tattoo, which isn't very Abnegation of her.