For me, it's pretty easy to play champions before they were cool because I generally stick to my champion pool regardless of what the meta calls for. As a result, there were some champions that I definitely played before they became cool.
For a while I started playing Trundle and Shyvanna top before Season 4's supertank top lane meta came into being. I liked to play both champions, but I started liking them less in the jungle, and at the same time I was looking to broaden my top lane champion pool, and really enjoyed playing both of them in the top lane. Eventually, Shyvanna became one of the three top laners that defined the "super-tank" meta, along with Renekton and Dr. Mundo, while Trundle also rose up in popularity because he countered these champions (definitely Renekton, not sure about Shyvanna and Mundo).
Viktor was also my main in the mid lane ever since I started playing back in Season 3, and eventually he became a staple burst mage among quite a few players fairly recently.
Likewise, I also played a bit of Nautilus support (I didn't play support a lot, but when I had to fill as support Nautilus was my go-to champion). Now it's definitely a thing.