Well I know Sombra was a bad villain. But most seem to think he took over the kingdom, as in he was an outsider. Others think he fell for the Princess and it all turned bad. But what if he WAS the King to begin with? What if he had no need to take it over, what if something else was the cause. Who was he then, before this?
Another take could be if the Elements had been used to purify him as was done to Nightmare Moon. Just something to think about I suppose.