Reporter: After spending nearly half a year living away from her own family, Bridget is finally back, and so is that trademark smile she's so often flashed as a little girl. So now, I can touch my... See More
Reporter: After spending nearly half a year living away from her own family, Bridget is finally back, and so is that trademark smile she's so often flashed as a little girl. So now, I can touch my mother and my brother and my father, and I'm living back at home. So I guess it's pretty much full circle. Reporter: Sharing a meal with the same family that she was once so terrified of, terrified that they would contaminate her. She takes us to her room. So I do my school work on the floor here, just here. And then I sleep here. I can't actually use a blanket because I don't know who has used the blankets before. Reporter: And Bridget, every day, remembers Dr. Weg's words. You have to face your fears. It's flying into the darkness. Reporter: But flying into the darkness still isn't as easy as it sounds. She takes us through the house to the doorway of the den where she stops. She tells us she can't go in. Do you feel like it's creeping back a little bit? Yeah, absolutely. Because I'm very good at avoiding things and making it look like that I'm not avoiding it. That's how my mom doesn't know it. And I don't even think she noticed that I haven't been in the den. So I'm very sly at that. But, it's -- Reporter: Mom, did you notice? Oh, I noticed. It would be, you know, "Bridge, come sit in the den," so she would come sit in the den for, you know, maybe five minutes, and that would be it. Reporter: Now, Bridget admits she can't make herself go into the den at all. It is a major step backwards. Do you sense pressure from other parents who might say, "Why don't you just make her go in there?" Because I've tried that and she just breaks down completely when she's not ready. And that's a horrible thing to see someone, you know, go through. Reporter: We notice her brother sitting in the den. He knows his sister is still tormented by fear. I'm curious what goes through your mind as you're watching your sibling struggle through this. We know that this isn't her fault, you know? I think that there's probably a point when she thought that we were blaming her for this. And that's definitely not the case. Reporter: He told us he's proud of his sister, and then he revealed something about his mother. How proud of his mother he is, too. Do you feel sorry for your mom at all, given what she's been through? Oh, well, I always knew, like, if anyone ever asked me, I would say that my mom is the nicest person in the world, and I'd, you know, stake my life on that. And it's definitely a difficult process for her and I think she's a great woman and I'm good -- I'm glad she's my mom. That's very nice. Becker, come here. Reporter: The whole family taking it one day at a time, all for Bridget. While for Michelle, that time has arrived, that prom she so feared. We snake our way through all of those kids looking for the 14-year-old who once couldn't get out of her own house, the teenager who couldn't step inside her own school. Now after all of that, on the other side of the dance floor, we found this. Michelle, dancing with her friends. And just outside, her mother, out of sight, wondering if her daughter is out of the woods. How is she doing? Reporter: She's tearing up the dance floor. No, really? Reporter: She's on the dance floor. Oh, that's a big thing for her. Reporter: Big smile. Oh, mom's proud. Reporter: Are you proud? Really proud. Reporter: And another moment we thought unimaginable when this journey began. Bridget getting into the front seat of the car with her mother, something she couldn't do just a few months ago. And where were they going? To the pool Bridget has so missed, the water she so loved as a little girl. We are about to try it again. Are you ready? I'm ready. Reporter: Bridget told us it is hard to believe she's here. What are you gonna show me, the butterfly? I'll show you some butterfly. Yep. Reporter: Show me how it's done. Yeah. Reporter: We were there the day you told Dr. Weg -- Mm-hmm. Reporter: -- That you were going through this therapy so that you could swim again. Yes. Reporter: And we're here. Yes, we are. Reporter: Should I time you? No. Reporter: That wouldn't be fair. We watched, and she was off. Bridget back in the pool. And that butterfly has come back to life. And for the mother who never gave up? I can't put it into words. It's just such a good feeling. Reporter: You've come a long way. Yes, I have. Reporter: But we all knew that day that this was just the first lap. We promised we would stick by them for the journey, and tonight, five years after we all first met, where is Bridget now? Where is Michelle who made it to that prom? And where is Rocco, so worried to leave his house? We go back for one more visit. And you're about to see a holiday weekend reunion we will never forget. ]
This transcript has been automatically generated and may not be 100% accurate.