Panic mechanic: Highly strung person who constantly fears the worst, gets riled up over any situation that's less than perfect, and wants anybody in their proximity to share their anxiety.
We all have them in the office: that individual who makes everything "urgent" and cannot stand to see you calm and unstressed. They themselves are prime candidates for a heart attack and want to drag any willing or unwitting party into their world of high blood pressure and anxiety. They perpetuate stress and are toxic to be around.
Each time they need something the entire company will apparently grind to a halt if they don't get it. "I need those minimum order quantities urgently, preferably by lunch today please. If you don't provide it the production line will stop and you will then have to answer to the VP. I don't want that to happen to you." They use veiled threats like possible reprimand from a senior and adverse consequences on the company as fear tactics.
Of course, the best way to handle a panic mechanic is not to deal with them at all, but while you're an employee that isn't always an option. Often part of your job function could involve supporting such a person with information or reports that you are responsible for. In such cases they're unavoidable. Until you become self employed, the idea then is to minimize the effects such people can have on you.
Email is your greatest ally
"Put your request into an email and I will action it. I will forget if you don't put it in writing." Nip the panic mechanic in the bud. As they start talking to you, cut them short, pretend you're preoccupied with something else and tell them to email you their request. You need to hammer the message into them that email is your primary means of communication and that you only talk as a last resort. This is the first step towards getting them to talk to you less. If they still persist with talking for much longer then cut them short again and tell them you're preparing for a meeting in ten minutes. It can be a blatant lie but it sends the message across.
Also, panic mechanics often return a day after asking something of you and will claim to have asked for it several days prior. Given the information overload most people work under, chances are slim you will remember when exactly they made their verbal request. Email provides great cover against misinformation and prevents a "You-said-I-said" battle.
It doesn't matter how impervious you think you are: when someone speaks in an alarmed tone and starts mentioning everything that can go wrong, you will react in some way to it - you heart rate picks up and the mere act of thinking about what they're saying is enough to take the rest of your day off the rails. Think back to any bad day you had: it was usually triggered by just one crappy event or comment from someone. Do not outwardly show any reaction to somebody's urgent tone of voice, however it may be affecting you inside. You need to condition them to speak to you calmly whenever they do talk to you.
It's in your eye contact and body language: look more attentive and look them in the eye when they are curt; look away and become disinterested when they start fretting. It's like teaching a dog to sit when it wants a biscuit: if the panic mechanic wants you to be collaborative and patient they must first speak to you like a professional. When they go into panic mode, that's when you become unhelpful, uncooperative and disinterested. You can convey these nuances without saying a word.
When they don't get what they want, offer them a solution, not remorse
If something isn't done on time, offer them a solution. So if you fall overdue on something you owe them simply give the panic mechanic a revised date by which they can get whatever it is they wanted. When they harp over your work not being done on time, do not apologize and just keep redundantly repeating your solution to them. This sends the message that whining will not make you work any harder or faster.
Here's something else: if they keep probing as to why you didn't do something (which they often do), make an excuse up (yes, fib) as to why it couldn't be done. Cite something that was out of your control. Telling the truth to people like this that you just didn't get down to it yet is a mistake. Do not give them any leverage because it sets the precedent for future requests from them. Their requests in fact will turn to outright demands once they know you were complacent or somehow let something slip through the cracks before, and then you won't have a leg to stand on when they become demanding. With certain people, honesty can come back to bite you.
No matter how nice they may be outside of the office, don't befriend them
Always stay formal and do not make idle chatter with a panic mechanic in any circumstance, even at Friday drinks. They actually need to know that you don't like them. Not liking someone doesn't mean you despise them; but it's just a way of putting a wall up and making the panic mechanic hesitate before talking to you. Make some chatter on Friday evening and next thing they feel more comfortable to turn the screws on you the following Monday. For highly strung people work will always come before pleasantries. The tragedy of it all is they often aren't conscious of how stressful they are to be around.
This approach can seem cold, but a panic mechanic has the power to spoil your entire day if you let them. They aren't good for you and besides muzzling them, diplomatically shutting them out is the best option you have.