[@BrassOtter] Excellent questions. As far as robots for characters, it rather depends. This is a world where almost everyone has been augmented in one way or another; cybernetic limbs more common than not though that technology in itself is still new and developing (see 'Science and Tech'). So as long as those rules are followed, there is no limitations for characters that way.

However, if you are looking for a fully functional robot like GhostShadow's character... these boys are incredibly rare and would be only "working" in zone alpha uNader government law. Now my character, Katherine Saunders, is a robotech student and has made little bits to help her around the house, but these boys are limited to just your basic "android" and don't function enough to base an entire character off of.

Hope that makes sense.

Also, if you want to do a brother/sister duo I say go for it. It will only fill in one spot of the 4.