I got into fountain pens for a while. One big problem with them is that you really need paper that's designed for them. A lot of common paper ends up wicking out the ink way too fast.
But they are still pretty cool writing implements. It's easy to change the nibs in them so I would recommend trying out a few different sizes and styles to find one that suits you. It's a fun experience even if ballpoint pens are overall more practical.
I always got on fine with laser printer paper. But it was never really a hobby – my school required them at one point and at another my parents thought it would help my handwriting. If you have a bunch of school kids made to use fountain pens, they aren’t going to be fussing about paper quality; they’ll just use what they have and be fine with it. I think you don’t really need certain types of paper. People just like throwing money at the bits of their hobby that are easy to throw money at.
In my experience, most laser printer papers feather heavily with fountain pen ink. I buy the Target brand ones, and they handle FP ink decently well.
But yes - you definitely need paper that handles the ink well. Most notebooks sold in regular American stores do not. If your city has a Kinokuniya[1] store, likely most stationery sold there will handle it well as fountain pens are still used a lot in Japan.
I ended up getting a Japanese notebook for that reason. I think the one I got may still have been a step up in quality from what's standard there, but it was a leap up from the generic US notebook I had been trying to use.
But they are still pretty cool writing implements. It's easy to change the nibs in them so I would recommend trying out a few different sizes and styles to find one that suits you. It's a fun experience even if ballpoint pens are overall more practical.