She becomes worried about her baby's survival, and when she goes into labor following a walker attack, Lori convinces Maggie to give her a C-section, despite the fact that it will prove fatal for her.
Lori dies giving birth, and Carl is forced to shoot her to prevent reanimation.
During season two, Shane gradually becomes more unhinged and shows bouts of irrational violence and bloodlust after allowing another survivor to die in an act of self-preservation.
Shane eventually lures Rick away from the group to kill him, but Rick kills him first.
While there are threats and incidents at the prison, including the death of Rick's wife Lori and the delusions Rick's grief causes, Rick and his group transform it into a relatively safe and productive community until they are forced out permanently by the Governor and his forces.
She attempts to comfort Shane so he will feel accepted in their group, but she is cautious about his reckless actions, and ultimately warns Rick that Shane is dangerous.
Shane's reanimation after being stabbed was the first concrete indication to the survivors that it didn't matter how someone died: they would still come back as a walker.
While Rick claims Lori's baby as his daughter, it is strongly implied that Judith is Shane's biological child. Believing Rick to be dead, she begins a relationship with Shane, but is loyal to Rick once he returns, and she pushes Shane away from her and Carl, of whom she is fiercely protective.
When The Governor attacks for the final time, he and Carl are separated from the rest of the group.
With Rick severely injured and unconscious, Carl reveals his anger towards his father for failing to protect the group and his mother.
He eventually makes his way to Atlanta and then to the survivors' camp where his family is taking shelter, and quickly becomes the leader of those survivors.