Nightshift-Only characters are characters who are applied for, added to the roster, and then randomly selected each nightshift to antagonize the patient characters. (More on how to apply for one
here.) To give more details on how much power NS-Only characters have and what they can do ICly, here's a list of rules and guidelines similar to the SC rules but tailored to NS-Only characters in particular.
1) Your character is working on the Institute's side, and their main goal is to stop patients from proceeding any further through the Institute's grounds and to get patients to go back to their rooms. However, your character doesn't necessarily need to be fully aware of their orders; for example, if you had a character in mind who was a robot specifically programmed to work for a particular company, they might have been reprogrammed/brainwashed to think that the Head Doctor is the head of that company and nothing much has changed about their orders.
2) Your character has all their normal powers, clothes, weapons, defenses, etc., so long as they aren't to a godmodding extent. Your character should be powerful enough to take on several patients at once and have the upper hand, but they should have enough weaknesses that they could be feasibly knocked out or forced to retreat.
3) Your character has explicit orders to NOT kill any patients. They can badly injure them, immobilize them, or knock them out, etc., but killing is a big no-no. (The only exception to this is if you work something out with a player who's looking to get their character killed off.) However, as the Head Doctor is the kind of guy who wouldn't want the patients to know they weren't in complete mortal danger, your character is in no way obligated to tell the patients this, and is in fact encouraged not to.
4) If your character is knocked out, they're free to be looted by other patients. Although all of their clothing, special items, weapons, etc, are free to be used during that entire nightshift by whoever grabs them, (albeit with some limitations if the items are overly powerful), only ONE possession taken from your character will still exist in the morning. (So, for example, your character has a gun, a bullet-proof vest, and a helmet. Although three different people take those three objects once your character is knocked out, only one of those people will still have the item they looted once the morning comes.) What gets kept and who gets to keep it can either be worked out amongst the players, or, if people decide to compete for one or more objects, we mods can be called in to randomize who gets what. ;)
As far as how attacking other characters works: Basically, you choose a location on one of the maps (a room, a hall, or an area outside), and run it by us mods to make sure no one else has claimed it or that it doesn't pose any logistical problems. Once you do that, you wait for an unsuspecting character or group of characters to enter your assigned area, and when the time seems ripe... BOOM! You attack! Still, some guidelines you should follow are...
1) All the fighting against your character should occur within one thread. Yes, we know that this makes posting harder than if one antagonist is going after smaller groups in different threads, but one person jumping from thread to thread is bound to cause some continuity errors or godmodding, regardless of how accidental those actions are. Also, this way, characters can skirt around the fighting if they want to or can jump in just as easily. The exception to this rule is if your character completes a fight with one group of patients (as in all their opponents have been knocked out or have run away), and decides to go on to a completely new bunch.
2) Your character may be powerful, but that doesn't mean they're invincible. By apping an antagonist, you are devoting the utmost responsibility to keeping up good communication with the other players in your thread so that there aren't any misunderstandings about attacks or how they damage characters. Also remember that it's just as easy for other players to slip into godmodding during a fight as it can be for an antagonist, so don't be hesitant to let us mods know if you think something is awry. It's happened before, and we're happy to help sort things out!
3) If no one enters your area after a couple of days or so, you're perfectly welcome to ask us to re-assign your character's area to somewhere that would be more active and fun.
4) Your character may not leave their assigned area without permission from us. We basically have the assigned-areas rule so that patients won't feel so ganged-up on as they would if we had NS-only characters running amok all over the place, but if you want your character to give chase and the players of the people you're chasing totally want you to do that too, you're perfectly welcome to so long as you run it by us and we give it the go-ahead.