That's awesome Ray. I can see lots of natural talent in that drawing just waiting to be developed and I love it. It reminds me of when I first found my interest in drawing and coloring as a very young boy. For me it was Fred Flintstone and all of the characters on that show and then I moved on to drawing the Road Runner and Wiley Coyote, Mighty Mouse and many others that I'm sure only a few can even remember. Every day at prime cartoon time on TV (and we only got like 5 channels back then) I was camped out with all of my art stuff and ready to draw.
I hope your grandson gets lots of encouragement to stick with this interest in drawing. The trend to rapid improvement will continue as long as he continues to practice and enjoy what he's doing. It's pretty wild: To this day... I can still free-hand draw all of those characters without even looking at anything.... although it's almost 58 or so years later Thanks for sharing.