I did this relatively recently in response to what my coworker did last year that I've never forgiven them for. Also a bit on the long side.

I (27M) work at a office building that is in a largely black and Hispanic area. The coworker (43F) whose earned my ire is white, I'm mixed Asian and the coworker (24F) that got fired was mixed black for a lil context.

At our office we have two lunch shifts so who you go on lunch with isn't always the same. Most of the people I hang out with at lunch shared this particaly shift with me so we decided to eat together in the staff lounge while getting some extra work done. We were joined by our older coworker, I'll say Melissa, who always uses the lounge an usually had it to herself. She made comments here an there about how we were to loud an boisterous to get any real work done, over all making it super obvious she didn't like that we were there. At one point one, call her Sonia, almost dropped her drink on her laptop and swore. Melissa snapped at her immediately telling her off for unprofessional language. We didn't take it very seriously an Sonia bowed her head saying 'okay master' leaving Melissa absolutely red in the face before she left the room. We chose to pretty much stick to going out or having lunch in the courtyard from then on thinking nothing of it. Not even a week later Sonia get's called into HR and without warning gets escorted out of the building with a mass email saying she was fired for discriminatory acts. Which was completely surprising as she was new but one of the most professional an strict workers I knew, she stayed late and got there early she was a crazy hard worker and was incredibly kind to everyone. Not even a full work day had past before Melissa was bragging about sticking it to her and about how she had directed HR her way for her 'unscrupulous' attitude. Everyone was livid at her but she was in another department so our complaints didn't go far. The most our department head could do was let us send her a gift basket an delete the email long after everyone had seen it (since it technically wasn't legal for them to display why she got fired) but it pissed me off for months until I heard Sonia had gotten a new job an was doing really well before I eventually just forgot the whole thing.

Nearly a year later we had a big downsizing in our marketing department so a ton of their staff ended up coming to our side to cross train. One of them was Melissa and as soon as I saw her again I felt angry all over again. It didn't help that she was completely disrespectful to the people training her. She was the definition of crotchety but also unreliable as she'd call in or leave early a lot. Like a whole like every other day something was 'wrong' with her. An it was always some type of allergy to some new thing that she happened to smell or see or even hear the concept of. A lot of it was very off the wall an she never seemed desperate to get to hospital for these very deadly allergies she was always saying they were so I got bored an started a list of every new allergy she came up with, with a time and date to go with it. Some of the things she's gone home for were strawberries, raspberries, water melon, blueberries (after previously saying they were the only berry she could eat), white fish, fish with breading, shrimp, garlic, any type of curry, pepper , red candy, anything with red dye in it, Alfredo, red sauce, msg, the smell of uncooked wheat, coconut shavings (had eaten a snowball the day before), dark chocolate (while eating strawberries covered in chocolate), said she almost feinted when a coworker was drinking a hi-ci to close to her. That's only some of the things too.

After watching Melissa get a little to huff puff on a new worker am sending them into tears I decided to poke HR as a concerned coworker looking out for Melissa's health. Since were required to have epi-pens on site for any allergy no matter how minor, I pointed out all the collected allergies I had learned about an almost all of them they had had proof of her saying or writing them in an email. After a few weeks they'd obviously gotten to Melissa about it as she was openly complaining about them forcing her to provide an epi-pen or some type of medication. Later I found out form someone in clerical she claimed it to be a money issue the said they'd provide the funds as her saftey was their upmost concern an she still refused. Eventually they required her to get an allergy test to which she eventually did.. an it came up empty. She wasn't allergic to a damn thing! An I felt so vindicated finally she was getting called out for something, maybe not her behavior or going after new staff but something.

I was so over the moon I didn't notice she was gone for almost a month when I saw her again. She was pale an shakey the whole work day, she ended up calling in more then she had ever before. She looked like she wasn't eating anymore an no one had seen her at the cafeteria once since she came back. I didn't know what to think till one of my friends suggested she might be hypochondriac or genuinely think she's having reactions. The more I thought about it the more I felt really bad about going so far and being invasive especially with her looking like she was on deaths door everytime I saw her. I don't know if I caused her to start starving herself or not an if I just got to caught up in getting some way to get back at her for firing my friend awhile ago. Idk am I the asshole??