Rangers are not yet in the game, and the classes that are in the game are still having their abilities changed/modified. Given that, there's no guaranteed answer to any such question. Our current info is that no class can permanently make a NPC mob into their pet. Ranger's are planned to have an ability to make a hostile mob into a friendly one temporarily. No details yet.
Some years ago there was talk of all classes being able to temporarily ride an NPC mob by first 'taming' it and then mounting it. Once dismounted, the mob went back to its previous, non-tamed state.