The core issue here is that the concept of "fear" is an emotion that our brains give us to keep us alive. Meaning that it's something a bot writer (or evolution) needs to actually build. There's no way to add a concept of fear to the program and have bots respond by running away or whatever, because "run away" is too nebulous a concept to enforce on the actual program level. Of course, there's nothing to prevent someone from coding in something like fear in their bot and having their bots run away when out numbered or out gunned or whatever.