Elegant Writer is a special type of water-soluble marker that bleeds in various colors. They have chiseled nibs and are probably made for calligraphy. I couldn’t remember when I bought my set, but somehow for many years, rarely used them. It’s time to give these markers a chance before they completely dry out.
Black Elegant Writer on paper:

Add water to the above drawing:

Blue and black:

Testing other colors:

A few notes:
- I used regular Canson drawing paper, and I believe to what extend it’s soluble depends on paper. So test it.
- The black one is the most interesting. It bleeds in blueish, greenish and reddish gray and really adds to the drawing.
- The blue one gives out some pinkish hue in addition to blue, but the green, red and the brown ones are pretty much just their own colors.
- The red, blue and green colors are more staining than black.
- I have no training in calligraphy, but I can see a trained hand could produce more interesting lines with a chiseled nib.