I drew these guys with a Pilot Custom 823 FA and Platinum Carbon Black ink. The FA nib has a good drawing width on watercolor paper - one of my favorites. It's a soft nib but I don't use the line variation, just some nice shock absorption with each downstroke. The Carbon Black ink is out-of-this-world good, though being pigmented I fear keeping it in too many pens.
This was done on a heavy day. On days like this, I like to doodle whatever is inside my head to lighten things up. My therapy. Almost everything in here means something.