Webcomic Concept Art

I have been working on designing characters for a web-comic. I have not yet created a plot (it will be plot based), and am simply working on the characters so far. I have two sketches, one with coloring. One is the armor of the main character, and the other is the face of the female scientist who is a second main character. It will be in a science fiction setting.

Here is the armor:

I know that the legs are very poorly proportioned; it's just meant to be ideas.

Here is the scientist:

This is only for face and such. Not for anything past the neck. 

This is all that I have designed so far, but I will be working more on this. Any input on what hairstyle the scientist should have would be appreciated.

And here is a sketch I made of a troll, just for the fun of it.

A big feller who looks like he eats rocks in his spare time. And elves.

Thanks for viewing!