Ela parece sofrer de alguma forma de instabilidade mental. Não está claro o que ela sofre, mas ela parece ser psicótica pensando que os caminhantes ainda são pessoas e alegando que ela pode ouvi-los.
Há um monte de evidências disso na Wikia Walking Dead.
Lizzie Samuels - Wikia Walking Dead
- Lizzie is shown to have mental instability and adjustment issues:
- She names the walkers at the fence, insisting they are still people.
- She feeds live rats to walkers. The feeder was unknown for a long time, but Tyreese confirmed that Lizzie confessed to it.
- She rubbed her foot around in Glenn's blood as Hershel was trying to save him.
- She kills and mutilates helpless rabbits (and other animals) without eating them.
- She seemingly tried to suffocate Judith by blocking her mouth and nose as she cried.
- She also tried to kill Judith again shortly after Mika's death, but Carol and Tyreese arrive in time to stop her.
- She admits to Carol that she didn't mean to shoot Alisha in the head because she wanted her to be able to come back as a walker.
- She allows a walker to chase her and flies into a rage when Carol kills it. She insists she was playing with it and that it wouldn't
hurt her because it just wanted a friend.- She admits to her sister that she can 'hear them' while looking at an incapacitated walker, explaining why she understands them. (She then almost allows herself to be bitten to 'change'.)
- She murders her sister Mika to show Carol and Tyreese that when she comes back she will be the same, similar to when Ben murdered Billy
in Volume 11 of the comic series for the same reason.- After murdering her sister, she assumes that the reason Carol wanted to talk to her in private is because she is mad that Lizzie pointed a gun at her, instead of because she murdered her own sister and was going to do the same to Judith.
No que diz respeito à minha própria teoria, acho que ela teve algum tipo de ruptura psicótica durante o início do apocalipse zumbi. Acredito que sua mente provavelmente se partiu devido ao surto e ao caos que se seguiu.