does anyone know if you can get an s/o in game? if so how?
That's about as far as it goes if no other characters get involved. Cassie's route needs to be worked on to take it any further, as doing so will lead to someone else working in the Torture Rack.
To start things off, you need to find the guy that charges 5 credits to let you pass and deliberately get past without paying.
Feel free to look up the wiki for Cassie's route, though. It's quite complex and has several possible Game Over endings.