Big Soap is Lil' Soaps big brother. He sometimes makes fun of Lil' Soap1), but protects him from bullies like The Government. They live together somewhere in the mountains surrounding Cyber city 404 where it never rains.2)3)4)5)

1)
For his shortness.
2)
They melt when mixed with water.
3)
They also have a cleansing effect when wet.
4)
From this it can be determined that they are actually the children of the Wicked Witch of the West, a gifted monkey trainer
5)
We're off to see the wizard! The wonderful wizard of Oz~ Don't get wet now!