Before being adopted and named by the Thing of the Fantastic Four and his wife Alicia Masters, Princess was a stray dog who kept following Thing around the Fantastic Farmhouse, located in Benson, Arizona. Much to Thing's annoyance, he kept chasing Princess out of the property all week long, going as far as putting a no dogs allowed sign outside.

This was until one night on a Friday, Princess and Thing get trapped in one of Miracle Man's illusions, where the house was falling down a bottomless hole. After finding out this was an illusion and that Miracle Man was behind it, Thing knocked the supervillain out and went to the kitchen to get some turkey bacon for Princess. Not eating any of the turkey bacon, Thing discovered that they were still in an illusion, thanks to Princess' nose. Proving that the illusion wasn't real, they both returned to the real world.

After defeating Miracle Man, who was looking for some of Mr. Fantastic's technology, Thing gave some actual turkey bacon to Princess. Soon they were both discovered by Alicia and the other members of the Fantastic Four in the kitchen. Later, Thing decided to adopt the stray dog and name her Princess Masters-Grimm as Miracle Man was being taken away.^[1]

Eventually, Princess met her owners' adoptive children, Jo-Venn and N'Kalla, who had been sent, along with the rest of the Fantastic Four's children and the Baxter Building, exactly one year into the future in a desperate ploy to defeat invaders from the Negative Zone.^[2]