One of my first otps from literature as a small child was Shasta and Aravis from The Horse and His Boy by C.S. Lewis. I LOVED Aravis. I loved that she was  such a strong and vocal girl in a country where girls were taught that they should be silent. I loved that Shasta and Aravis fought throughout the whole book, yet the times they spent apart they felt less grounded without the other to back them up.