Someone believes they are the only person with highly strategically useful powers. However, they can't make the best use of them without revealing themselves, so what countries would be the safest places to do that?
An example of an appropriate power would be: The ability to very slowly open and close portals, as a long ritual that requires your hands to be free. As the power is limited enough that a country like the US could easily hold you captive indefinitely. Remote sensing is an even better example power as a nation could easily hide their use of it (though a worse example in that you staying secret is actually feasible).
Essentially you have powers so useful most countries would try to kidnap you and use you as a weapon/strategic resource given the chance.
Assume that we are going with the most uncharitable plausible prediction of governments, organizations, people, etc based on their past actions. That being said few organizations that could protect you here lack scandals that suggest they are constrained only by PR not by ethics.
So what countries are you most likely to be able to seek refuge in and negotiate with? That won't just take what they want from you by force..