Here are a few simple steps to dealing with a patron that, for one reason or another, has gone batshit crazy:
1. Speak Slowly and Confidently. People often underestimate treating adults like children. In fact, the type of people that cannot function in a public setting are often children. If you treat them with respect and calmly explain the situation, often they will not understand you. Talking down to them simply puts them in a better frame of mind to deal with the police later on in the evening.
2. Do Not Move Toward or Away. As in dealing with any animal, body language is key. Stake your ground and hold it at any cost. Moving toward them is an attack, even if you just wish to hug it out. Moving away from them is a retreat, which could trigger an attack from them. By holding your ground, you are saying that this will go no further. Avoid screaming "You shall not pass," though, unless the patron sets him/herself on fire.
3. Feign Eye Contact. Just like body language, eye contact is important in establishing dominance. By staring directly at the patron, you make them feel as if they are being heard before rattling off a preprepared speech. Fake eye contact by staring at some point beyond the person, often letting your vision go blurry as you fade into meditation. Do not focus on a part of the patron's face, as this could lead to finding grody scars and lesions that could distract you for your cue to give the prepared speech.
4. Make Yourself Appear Bigger. Again, dominance is key here. You must establish that you are a bigger threat than the patron. Lift your chin up, stand on your tip toes, or hold your jacket over your head to create a more looming presence. Wave your arms wildly above your head and make a lot of noise. This can scare off even the most determined patron.
5. Keep Something Heavy. When all negotiation has failed, a large heavy object can often be a deciding factor. While some librarians like the heft of the Oxford English Dictionary, I prefer the balance of the Webster's Collegiate. Knowing your strengths and weaknesses in combat can save your life.
6. Run in a Zig-Zag Line. If combat is not your forte or has failed, fleeing is your best option. If a combat hardened patron gives chase, it may have speed as an advantage as well. However, patrons are not good at cornering as the graceful librarian. Running in a wildly erratic pattern instead of a straight line can be the difference between life and death.
7. Cover Yourself in Mud and Go Hand-to-Hand. Negotiations have failed, combat is lost, and fleeing is only a temporary option. Now is the time to get dirty. Because a patron's vision is based on movement and heat, the best option is to cover yourself in mud or any cold substance (hand sanitizer can work in a pinch) and stay perfectly still. As the patron approaches, spring your trap, whatever that might be. I prefer a pit of sharpened golf pencils covered with a fine coating of Twilight novels.
Hopefully, this will never be you. The rigors of public library work can be demanding, and sometimes people just have a bad day. Do not take it personal. Just remember, you are there to help.