As I've said recently, the joy of writing fiction, particularly science fiction, is that I get to make things up. In reality, I've made very little of Echo up myself. The spaceship she rides and the rules that describe the design and how it travels owe a lot to the role playing game Traveller. The armour worn by the Bad Girls does more than nod to the Space Marines from Warhammer 40,000. And Echo herself takes her genetic make up from various heroines that appear in novels by Robert Heinlein, but none more so than Friday.
Even the weapons. Echo's bolt thrower, for example:
I didn’t want any nervous guards opening fire because they could see the shape of the bolt thrower under my arm. It was, realistically, a most impractical weapon. The revolving chamber was bulky, the length and weight made the gun unbalanced and the lack of a proper barrel made it wildly inaccurate at distances of more than fifteen metres. But, in close-quarters combat, the 8 mil discarding sabot rounds would penetrate every type of armour I’d come across and the bang of the high explosive warhead scared the shit out of everybody.
Can't imagine where I got the idea from. You take your inspiration where you can find it.