I really like these. I've been going back to doing a light red underdrawing and then ink on top. I think the trick is to stay loose in both stages, even when inking.
Also I was recently told by my friend Mark that someone stole his work and was passing it off as his own. You can read about it
here. Mark's original image is located
here.
My opinion with people taking my work has always been give credit where credit is due. And if you didn't create more that %90 of the work, it's not yours. That goes for animation, illustration and even coding. Unfortunately tracking this stuff is really hard with the availability of stuff on the net. I'd say it's up to you to decide on whats responsible, ethical and fair.