The other day, I had what was probably the worst experience with a patron in my career.

Everyone knows customer service is full of pitfalls. Sometimes they’re rude. Sometimes you’re cranky. Sometimes they’re vague. Sometimes you’re impatient. Afterward, you wonder what you could have done better—because usually there was a better way. And next time, hopefully, you’re ready.

This was not one of those situations. I was energetic, in a good mood, and ready to help. I greeted the patron, a stranger, brightly. I asked how I could help. And then we went down the rabbit hole.

This person rejected every single thing I said. She was angry. More than angry, she was accusatory. She was aggressive. She used intimidation: leaning across the desk, demanding to know my supervisor’s name, repeating irrational questions in a rapid cycle that, I swear, could be a real-life interrogation technique. What was most frightening was that she did all this without raising her voice.

Eventually, I was able to call another staff member to talk to her, but by then I’d gone cold and was shaking uncontrollably. I fled the department, sobbing. Since my usual reaction to difficult patrons is passive aggressiveness (though I do my best to keep it under wraps), I think it must have been the shock and unreality of the situation that triggered my panic. It was as if I’d offered her a cupcake, and she’d stabbed me in the hand.

It took half an hour for me to calm down enough to return to the desk, though I was still shaking a bit. In the meantime, this unpleasant patron had gone through two other staff members—one of whom already was familiar with her, and neither of whom was rattled the way I was.

Unfortunately, that wasn’t the end of it, and the patron approached me again, demanding to know my name and asking more questions I had no way of answering. She wasn’t as much in my face this time, but I didn’t want to risk her exploding at me. I did what any good librarian under extreme pressure does: I punted her questions to another staff member.

Here’s the thing: I’m not writing this to vent. I don’t really want to talk about this patron or the particulars of our interaction. But it’s necessary background for how I felt afterward.

First, I should admit that I have felt just a wee bit of temptation for revenge. Since the incident, I’ve learned this patron’s name and workplace. I could go there and make her life miserable.

But I have the feeling her life is miserable already. Whether she treats perfect strangers with such unkindness is because her brain chemistry is unbalanced or because she is going through difficult times or because she has a nasty personality, she is clearly not a happy person. I would take no joy in making things harder for her.

Earlier today, one of my friends posted this quote by John E. Southard: “The only people with whom you should try to get even are those who have helped you.” The words really hit me, because oddly, revenge fantasies aside, what I’d felt after returning to the desk was the desire to be kind myself.

I was already putting the trauma behind me, and I wanted to prove that it wouldn’t stop me from doing my job, and happily. Because making other people happy makes me happy! That’s another reason I felt so awful about what had happened earlier. I was doing everything right, but there was nothing I could do to make her happy.

Fifteen minutes before closing, I had my chance. One of our regulars, a retiree who loves bulldogs above all else in life, was heading out. “I have something you’ll want to see,” I told her and loaded up Cesar Millan’s Bulldog of the Year Gallery. We spent the next several minutes looking at the dogs in the gallery and talking about bulldogs. She seemed so surprised and pleased for someone to take an interest in her and her interests. It was so simple, but it felt so good to do that.

I know it wasn’t selfless, not entirely. I’d had a bad experience I wanted to put behind me. I wanted to reaffirm my belief that most people respond to kindness and kindness. I didn’t want to continue the Chain of Screaming.

But so what if it wasn’t selfless? It worked. And it felt so much better than perpetuating unkindness.

My supervisor knows what happened that day. It turns out I’m not the only one who’s dealt with this problem patron, not by far. Now the library director is in on the conversation. We have a script we’re supposed to follow if something like that happens again. Next time, I’ll be ready for her. It’s hard to imagine how things could be worse than the last time, because I’ll no longer be shocked by her threats. If she’s going to surprise me, it will be with kindness.

Before I sign off, I have one more confession to make. There was one downside of my act of kindness: the bulldog fan was back today and talked my ear off about her favorite subject.

It seems a small price to pay.