Sandra Bakers

Sandra Bakers is Ray's sister and is found by Ray and Nicholas hiding in the apartment they had barricaded. She is sixteen years old. She and her brother are accepted in the group and are immediately loved by everyone. Sandra is too young to help with firearms or supply trips, but her brother pulls her weight as well, not to mention her helping with the jobs inside the group, like cooking 
At some point she and Mat Davis are attracted to each other. Her brother objects but she reacts like a typical teenager and proceeds with the relationship. Ray tries to interfere and comes at odds with Mat, who is helped by Jason. Jason and Ray engage in a fight, but they are broken up by Michael. Michael is finally able to talk Ray into becoming a parent other than a brother, and Ray admits he has no idea what he is doing. Michael promises to help him, and Ray thanks him. He later allows the relationship to happen, but still has problems with it and doesn't feel comfortable, nor does he like Mat.
A while later, Sandra is impregnated by Mat. Although Ray and Mat's father didn't allow them to have sex, they did so without protection and she got pregnant. She finds out when her period is late, and the next time Mat goes on a supply run she tells him to bring her a pregnancy test. Mat is shocked at the possibility of her being pregnant, and he is careless throughout the whole mission. He almost gets bit too, but Jason saves him and then yells at him for being careless. Mat then starts crying and confesses to his brother, who consoles him and tells him to give the test to Sandra to take, and then figure everything else out depending on the result. Sandra takes the test and it comes out positive. She cries and gets mad at Mat, and doesn't know what to do. 
Mat lies to Jason about the result, and Jason is relieved. Mat knew that Jason would want to tell his father. He and Sandra promise not to tell anyone and that the next time Mat goes on a supply trip, he will get some abortion pills for her. 
In the next trip though, Ray loses his legs and mat gets bitten. With both of them ready to die, Michael and many others protest and demand from William to give the cure to Mat and Ray. Ray is amputated though and is not infected, but Mat is. William doesn't give it to him at first, saying that this may be the key to defeating the aliens, but Christine intervenes and tells William the truth about Sandra and that things don't look very good for Ray. William then decides to give Mat half a dosage of the cure and he is cured after two days of adjusting. His body powers are now pushed to the maximum. 
When Ray wakes up and he is alive, he has depression and pushes everyone away, so Sandra doesn't burden him with her condition too. Shortly after Ray commits suicide and Sandra is horrified. As a result, she loses the child and enters a state where the trauma is too much for her to handle. When she has the miscarriage, it becomes known that she was pregnant, and Michael gets angry at Mat. He slaps him and says he is disappointed in him. Mat then tries to reach uot to Sandra, but she says all this is his fault, and it all started when she started seeing him. Mat, overwhelmed and feeling unloved by everyone, steals the cure and heads for their home, where his mother is, hoping to cure her. 
Sandra is now taken care by Christine, who is dedicated on making her feel better. Feeling guilty over Ray's death, because she didn't help him because she was too preoccupied with her cancer, she is now dedicated to take care of Sandra and help her get better. When Ray lost his legs, Christine talked to Sandra too and Sandra got close to telling her about the pregnancy but she didn't in the last second. 
Mat is thought to be in his room, while Jason and Michael argue over him. Jason supports him saying that he is a teenager, and what he did was normal, but Michael argues he endangered everyone and that no one can think like the world hasn't ended. Michael then breaks down and says he is also clueless about what he has to do, and that while they are as safe as they can with the group, he doesn't know how to raise them without their mother. Then he adds that his reaction was bad and unfair, and the only one he was angry at was himself because he couldn't save his son. He also says he is proud for him standing up to him and making him see sense, and that he is a good brother. They then go to Mat's room to apologise but see him gone and the window open. Mat, having taken the remaining cure goes back to his home, and Michael, Jason and Williiam follow im closely. When they reach the house, they hear a gunshot and slowly after Mat comes out of the house crying. He ignores his father and passes by, but Jason grabs him by the shoulders and Mat cries in his brother's arms. He gives William the vial with the cure, who doesn't say annything, and Michael just stands there too. "How could you?", Mat finally broke the silence. "You are weak", he told his father. "That thing in there wasn't mom, and could never be. How could you leave her like this? Do you have any idea of the suffering she went through?". He later started yelling about Michael slapping him and telling him he is worthless. Michael just stood there, while Jason took Mat back in the truck. William told Michael to come back, but Michael said he needed to bury his wife and he would return with the motorcycle Mat came. William nodded and promised to take the kids home safe. Michael buries a grave and buries his wife before returning home.
After this, Sandra spends her remaining time with the group and never gets back with Mat. 
When they reach the military base, she is the one to tell the general that Mat has survived a bite, and he is taken in for experimentation. She hides the fact that Christine survived a cancer the same way, because she likes her. When the group leaves the military base, she stays behind as she has no connections to them anymore. In the final battle, it is revealed that Sandra has become a great soldier and fights there too. She is also killed there.