They are both incontinent. In a physically abstract sense, Grid is constantly wetting Themself in a never-ending flow; and Get occasionally wets or messes Themself. Their Diapers are quite necessary.
Societies necessarily invent the concept of incontinence as part of a response to disease; incontinence is only significant when it's considered unsanitary. When a society within Their domain invents diapers as a widespread tool to manage incontinence, The Otters consider that to be the strongest indicator that the society is viable and maturing. They interact more with the mortals in that society during this time. And if the society's medical science advances to the point where incontinence is completely curable or preventable, and everyone stops using diapers to manage it, The Otters lose interest and step back.
They, especially Grid, have the power to create worlds where incontinence and diapers are inevitable and perpetual, but it doesn't satisfy Them as much as watching it unfold organically. They know approximately what They'll get from a world when they first plant its seeds, but They don't know all of the details, so being surprised by the decisions of Their mortals is a critical sensation that further empowers Them both, and instills curiosity and mischief within Them.
They are both incontinent. In a physically abstract sense, Grid is constantly wetting Themself in a