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The expression is lovely in these pieces, they very much feel alive.

I think you could work on making more long movements with your pen - with your whole arm - to find a flow if you're looking to make your art less stiff and more dynamic. Perhaps try drawing on a bigger surface/thinner pencil - allow it to take up space?

Don't be scared to push the shading more for contrast. In the figure to the left, the hand/arm melts into the shirt and at first I read it as part of his shoulder. More contrast would help. Same goes for the shading overall.

The weight of the line is good, and shading where lines are as well, but elsewhere it's very "careful". The contrast between the hair and skin is good, but comes off as a bit blocky in places, dark and of same tone all the way through so you can't see its shadows and high lights. In this style that works well, but there's some room for improvement.

Overall - impressive work. :)

You have a beautiful understanding of anatomy and structure! Don't be afraid to push reality to add more life!