As far as I can tell there are three types of characters. Main Characters (Deryl, Michael), Side characters (Tiffany), and Sub-Side characters (Jake, Angelina). Rule of thumb; If you have the option to kill them, from the point of the choice onward they will have an extremely minimal impact on the story. At least thus far, they only really show up semi-randomly around the HERO base as conversationalists. If you want more corruption, eat them. I doubt it'll have any lasting impact.