Andrea/Season 1

Andrea was among the group members that volunteered to travel to the city for supplies. Later that day, gunshots had alerted walkers to their location, and the group was forced to hide inside a department store. When Glenn saved Rick Grimes and took him to their refuge, Andrea pointed her gun at the newcomer and scolded him for having endangered them all due to his recklessness. Shortly after Rick restored calm by handcuffing Merle Dixon to a pipe on the roof, Andrea began to warm up and respect the newcomer and helped him devise a plan to escape from the building. Andrea watched as Rick and Glenn were able to get a vehicle for the group to escape, although they were forced to leave a handcuffed Merle behind. ("Guts")

Upon returning to the camp, Andrea reunited with Amy with a hug and was also surprised to learn that Lori and Carl were the family members that Rick was looking for. The next day, while doing laundry at the lake, Andrea and the other women from the camp shared what they missed about their lives. When Ed Peletier confronted them for laughing, Andrea stood up to him and tried to defend Carol until Ed slapped his wife, and then witnessed as an enraged Shane brutally attacked him in a fit of rage. ("Tell It to the Frogs")

Some hours later, Andrea and Amy had gone fishing over at the quarry lake, where they reminisced about their childhood and how their father had raised them in different ways, concluding that he wanted them both to be special and unique. The sisters then returned to the camp with all the fishes they had caught for dinner and were congratulated for their effort. After Dale informed everyone at the camp about a paranoid Jim digging holes without an explanation, Andrea witnessed as Shane subdued him and tied him to a tree until he would feel better.

Later that day, worried about her sister's birthday, Andrea searched in the RV for wrapping paper to wrap a mermaid necklace that she had gotten for Amy, and then Dale offered to help her find something. That night, everyone was reunited around a campfire as they listened to Dale's stories. When the camp was attacked by several walkers, Andrea watched helplessly in horror how Amy, who had left moments before to use the bathroom, was bitten in the arm and the neck by one of the undead. Although she ran to rescue her sister, Andrea couldn't do much to help and was left completely devastated as Amy died in her arms. ("Vatos")

Having been left completely heartbroken due to her sister's death, Andrea remained very overprotective of Amy's corpse until the next morning, being willing to kill anyone coming near them. Dale eventually made her open up a little bit after talking about his wife's death. When Amy finally reanimated, Andrea held her in her arms for a few moments and apologized, before shooting her in the side of the head. The next day, Andrea was present in the last camp meeting where she said goodbye to the Morales family. While the remaining group of survivors departed towards the CDC, they left an infected Jim under a tree by the road as his last wish. Upon arriving at their destination, they found everything abandoned. As some walkers began to approach them, Andrea tried to convince Rick to leave when suddenly the doors opened in time. ("Wildfire")

Upon entering the CDC, Andrea and the others were reluctantly welcomed by the sole remaining employee, Dr. Edwin Jenner, who allowed them to stay in exchange for some blood tests. That night, the group had a feast in the cafeteria and enjoyed all the luxuries the facility had to offer, except for Andrea. Now in a state of depression, Andrea broke down in tears while showering and moments later she told Dale that, despite the idea that they could start a new life, there was nothing else left for her to live for. The next morning, Andrea and the group learned that the virus that had caused the outbreak erased any conscious human traits from someone infected.

When the power generators began to ran out of fuel, Jenner revealed that the facility would explode due to a self-destruct protocol and then sealed everyone inside the control room, explaining that it would be a quick and painless death. Convinced by his words, Andrea decided to remain in the building even after Rick made Jenner change his mind. Dale chose to stay as well in an attempt to convince her to escape. Not wanting to carry his blood on her hands, seconds before the entire facility exploded, they both managed to escape in time and took refuge behind some military sandbags as the CDC exploded. Andrea and Dale then joined the rest of the caravan and continued their journey towards a new destination. ("TS-19")