The True Lab
The True Lab is an AU created by Emma Yonemura. There aren't any special details suggested yet by the creator. After many nights spent on the plot of the story, on March 19, 2017, Emma started drawing the AU.
In this AU, Chara is portrayed as the protagonist of the series. Ten years before the story takes place, Chara was forced into the underground by her abusing parents. She then meets the teenager Dr. W.D. Gaster, a boy who had been forced into the underground with Chara. They become friends shortly after, and two years later, marry at 17.
Planning to start a family in a safe place, they both work on finishing the Core for their family and Asgore's family. While working on the Core, Chara gives birth to Sans. Now both 25, they strive to finish and finally be able to live in a happy place.
Then, the first human falls down while the Royal Family is moving. Their name is also Chara, and was named after their "deceased" aunt. Learning that another human has fallen into the underground, Dr. Chara rushes to the Ruins, but is sent back to the lab, because of a reset caused by them.
Dr. Chara and Dr. Gaster quickly realise that they have a special ability, and proceed to do tests on them. During this time period, Dr. Chara gives birth to Papyrus and has to take care of both of them. While testing Chara, Dr. Gaster is suddenly knocked out by their magical ability, as their soul turns into hatred for the humans.
Chara goes to the couple's house, and tries to kill Dr. Chara. They are stopped right there, as Dr. Chara captures their soul in a vial suited for souls. She then rushes to the lab with Sans and Papyrus in Toriel's care, to find Dr. Gaster passed out on the floor.