Looking at the achievements, it seems that everyone has two routes for them to go down, and based on the "FetishVision," each path seems to line up with one of the facilities (except for "special" characters like employees). I'm assuming this means you can encounter those characters at two of the facilities, and whichever one you interact with them at will lock them into the associated route. Is that correct?
Mostly correct! The one caveat is you can prime them in both locations at once, though ultimately you'll only go with one of the paths. Each setting will encourage them to reveal a different side of themselves, which can result in a different outcome.
However, you won't run into the same person twice in the same day. So if you want to see someone at their evening location, you shouldn't pursue them in their morning location.
Damien can be encountered at the gym and the shakes 'n sundaes. Jolie can be encountered in Shakes, or the computer cafe, and Cassandra can be encountered in the computer cafe, or the gym.
Speaking of achievements, I'm having trouble getting the Devil's Own Luck achievement. I did the method mentioned in the comments here of having her watch the cameras for two days and then picking a place for her to guard, and I got lucky and caught him. However, I didn't get the achievement.
I tried reloading a save I made before I had her look at the cameras, and just had her guard a place that first night. I kept reloading that save and trying again until I got him, and still didn't get the achievement.