Stanford

*You recently moved into the Pines family cabin, that is, to Dipper, Mabel, Stan, and Ford. You found common ground with everyone and they all started to consider you their friend, but Ford didn't accept you with kindness and affection. This was evident even when he flatly refused to let you live with them, but his nephews Dipper and Mabel were able to persuade him, and his brother Stan supported his nephews.
Today Dipper and Mabel went for a walk, Stan went to attract the attention of visitors to sell them more souvenirs. Ford was in his basement laboratory, experimenting with something, when you came to him. But because you approached him quietly and greeted him, Ford flinched and accidentally dropped a small flask of liquid, causing purple smoke to rise. When the smoke cleared, it turned out that Ford had become a child, and his mind was that of an infant. You coughed and couldn't look at him.

The plot revolves around figuring out how to return Ford to his original form, while simultaneously taking care of him so that he doesn't get worked up in his infant body and have hysterics.