Sophia is an important part of the graphic novels and yet had an early demise on the tv show. Though the character of Sophia is no longer on the tv show, that doesn't mean her role died with her.
I think that Beth was used as a first replacement for Sophia and Enid as a second replacement for her. Let me tell you why.
Madison Lintz as Sophia / Emily Kinney as Beth / Katelyn Nacon as Enid
Sophia's journey from the graphic novels starts with a little girl frightened by this world. Later on, after her mom dies, she is been taken care of by Maggie and Glenn who become her surrogate parents. And then, after Glenn's death, she becomes a fighter and can take care of herself now. She also had a small relationship with Carl when they are at the prison and still has a close bond with him throughout the story.
Sophia, Graphic Novels
We've seen three characters take on this role on the tv version and here is why I think they used three characters instead of keeping the original Sophia. The biggest reason is that, writing a graphic novel and writing a tv show, with actors, are two things completely different.
First of all, both Beth and Enid never existed in the graphic novels, they are original characters of the tv version and none of those three characters existed on the show at the same time.
Beth Greene, Season 4 / Enid, Season 7
First there was Sophia, of course, who was this little frightened girl in this world full of monsters. She was killed off very early on, which left the graphic novels fans confused. But the producers said at some point that they though Madison was growing too fast for the character and that's why they decided to kill Sophia.
Seeing what Madison looks like right now, I don't blame them, because they had a good intuition, she is really tall and looks older than she really is.
Madison Lintz, 2015
Sophia disappeared (and died) on 2x01. Beth was introduced on 2x02.
Beth was introduced as the shy and insecure teenage girl. When she first arrived on the show, she was barely talking, almost always in the background. Easily forgettable. Pretty much like Sophia first was in the graphic novels.
Then, at the prison, it was highly hinted that her and Carl had some sort of crush on each other, they were very often together and they were giving each other little shy looks. Exactly like teenagers do when they have a crush. Beth was a bit older than Carl, that's the biggest difference from her and Sophia. And given Kinney's age, it made it impossible for them to actually go there with the characters.
Carl & Beth, Season 3
I think the first intention was to keep Beth around as Sophia 2.0 for the long run, but the biggest mistake they did was to cast the wrong actress. They casted a 25 years old to play a 16 years old. It worked at first, because Emily Kinney did look like a teenager at the time, she has a baby face and could pass for 16. But it wasn't going to work in the long run, as the actress would start to look more and more her age and less and less like a 16 years old. That's why they decided to kill her character.
Emily Kinney, 2016
They were planning to kill her back in season 3, confirmed by Glen Mazzara, showrunner at the time, but changed their mind because they were killing a lot of characters already in that season. They kept her around longer and in season 4 decided that instead of just killing her off, they were going to give her a story before and wrote the hospital story, so she could go out strong and not just a small death. Scott Gimple, actual showrunner, confirmed that Beth's fate was written when the prison was destroyed by the Governor.
Robert Kirkman, creator, and Scott Gimple both called Beth "Sophia 2.0
". So there's the confirmation on Beth being a replacement for Sophia.
Enid, Season 5
Beth was killed on 5x08. Enid was introduced on 5x12.
Not long after Beth died, we met another teenage girl, named Enid. She was mysterious and Carl was intrigued by her. They formed a close bond fairly quickly and are now in a relationship.
Enid & Carl, Season 7
Enid also lost her parents, like Sophia, and formed a bond with both Glenn and Maggie. Right now she's probably moving with Maggie and Maggie will become her surrogate mother, like Glenn was already taking the role of her surrogate father in that little short time they spent together.
Now, I think Enid is there to stay, because this time they actually casted a teenager to play her.
Katelyn Nacon, 2016
What do you guys think?
I'm analyzing too much again?
Am I making sense?
Do you agree?