Chara being a mischievous little imp dared his adoptive brother Asriel to try drinking the water from the rivers of Waterfall. Unlike the magical food eaten by the Monsters commonly, the water was entirely natural, and would have to be processed by natural means. Thankfully Toriel was prepared for this and Asriel's waredrobe would have to be altered for quite some time.

It was time I started experimenting with the Ink tools more in CSP, and I think this came out rather well. I kept the under-laying sketch since I felt like it made the image pop a little more in what would otherwise be a largely white picture to begin with (even if it'd be black & white anyhow)

Asriel, Undertale and related concepts property of TobyFox