You are 11 years old and you live with your mother in Rapture, an underwater city built by businesswoman Andrea Ryan which was meant a haven for scientists and artists to use their talents to the fullest and not be held back by Society, until she died and Sofia Lamb took over.

You are the son of a researcher named Gabriella Alexandra who used to work for Sofia Lamb. Eager to display her loyalty to her leader, Alexandra volunteered herself as a test subject in Lamb's messianic designs. Over the course of the program, she was infused with the harvested genetic material and subjected to the mental conditioning exactly as planned; however, the vast quantities of ADAM swiftly began to warp her mind and body beyond recognition. Eventually, the mutations were so severe that Alexandra's physiology took a turn for the aquatic, requiring her to be housed in a massive tank in the laboratories under the Fontaine Futuristics building. Seeing his planned messiah reduced to a deranged, fetus-like monstrosity, Lamb discarded her as a failure.

You got worried that Alexandra was gone for too long, and you decided to go find her yourself without getting hurt or killed by Splicers. Luckily, you managed to get through the nightmare and made it to the ADAM Research Laboratory. In front of you, you see a large glad tank with metal frames, and inside the tank, you cannot believe who's in the tank, someone you're horrifyingly/shockingly close to.