I'm not kidding about the headlamp
You don't have to be on The Bachelor to find yourself in a shared house situation. Maybe you're splitting a vacation rental with your friends, maybe you're all teaming up for a destination wedding, or maybe you're there for a bachelor or bachelorette party. Regardless, at some point, you're probably going to have to cook. I love a group house, most of the time. I often volunteer to cook at them because, well, I like cooking, it's an easy way to contribute, and it's a good way to avoid group activities I don't love, like playing Never Have I Ever and golf. "Sorry, can't play Settlers of Catan or go on that run in 100-degree heat—gotta marinate the chicken!"
Rental houses will usually have plates and cups. Everything else is pretty dicey. Yours could have sharp knives and well-cared-for kitchen equipment, or you could open a drawer that you assume has cutlery only to be greeted by two dead spiders and a crumpled napkin that reads "It's Wine O'Clock Somewhere!" Both have happened to me. Here are four things that you should bring with you to make the most of whatever greets you at the mystery house.
A Knife Sharpener
Yes, you can sharpen a knife on the bottom of a mug or on the top of a rolled-down car window if you really need to. You can also buy a $5 corner knife sharpener, throw it in your bag, and rest assured that you can deal with dull knives. You could also, honestly, bring your own knives, but knives are heavy and sharp and expensive, and you'd be bummed if you left your favorite chef's knife at the house. A $5 knife sharpener? Eh, you're probably not going to cry if you leave without it.
This probably sounds finicky to you because salt is salt right? As anyone who has made the mistake of adding table salt instead of kosher salt to a recipe can tell you, the size and texture of the granules really matters. Kosher salt has larger granules and thus tastes less salty than table salt, meaning you can season things more easily without accidentally using way too much. I carry a pinch tin of Maldon salt around with me everywhere to season desk lunches, and it comes in handy in group houses too. So many things do better with that mildly salty crunch.
The seasoning situation in a group house could be great, or it could be a single 20-year-old bottle of dried thyme. Taco seasoning is wonderful for all sorts of things. You can use it to make tacos, of course, but it's also great on eggs, or rubbed on chicken or steak, or even sprinkled on melon. You can also use it to rim a bloody mary or a Margarita or to make a kind of delicious, non-authentic michelada.
My friends usually make fun of me for bringing this. Yes, wearing a headlamp in a casual, non-camping situation is a particular kind of look. But I'm never leaving it at home again. If you have to grill outside in the dark, and you're not sure about the lighting, a headlamp is crucial to seeing when those burgers are done. It's useful for checking if the pilot light is out, or if that's really a mouse in the pantry.
If you're feeling truly hardcore, you could also bring more spices or your own olive oil. I mean, go nuts! Especially if you have a car! (I don't.) But if you bring along these basics, it'll go a long way.