I've been doing a lot of sketching with a sharpie pen lately. It's pretty fun. It's not as bold as the Copics that I use to draw with. I like the way you can create a sort of sketchy look to the lines. You have to go over a spot several times to make it as bold and broad as you'd like. It gives it a really unique look; something I've tried to do before but never really had the proper tools, I think.
Something interesting about working with different types of art supplies is that it can dictate the way a sketch will turn out. Not just in the stylistic elements but in the actual structure of the drawing. For instance, if I was using a brush pen to draw this character, his proportions would probably have come out a lot different. Also, I might not have been compelled to do all those little wrinkly bits on the front of his sweater or the stubble on his face. You kind of just go with what feels right with the utensil you are using, and every art utensil is different.