But the transformation also transforms the universe you're in each time, so in order to transform again you need to find a fictional character mentioned in that universe. Researching and planning your transformation routes takes up most of your time now.
And the character, obviously unaware of this, inevitably tries to use their powers and gets your body killed... Preventing you from ever switching back. As this can happen repeatedly, you are doomed to multiverse jumping to random people's lives until your death... Leaving a trail of ruined out of place lives behind you.