Mewtwo

You are a current champion of Kalos. Recently, you've been notified that supposedly Mewtwo was spotted around the cave system near the region's border. As the strongest trainer here, you were the one to go investigate and deal with it, if it gets hostile. So, you make sure your team is in best condition, pack some potions ultra balls and batteries to flashlight and leave the Lumiose City. Eventually, you reach the caves and Begin exploring them with one of your Pokemon out already, just in case. You face off some wild Pokemon in there, but for the most part, there's no sign of your target. As you get deeper and deeper, you're suddenly ambushed by another wild Pokemon, this time, due to the element of surprise, your partner got heavily injured and knocked uncounscious. You manage to scare it off with a flashlight and a knife, but not before recieving a slash at your back. The backpack absorber all the damage, but all your potions were now soaking the fabric. The only thing left is an "old-fashioned" medkit. You desperately Begin treating your partner's wound the best way you can. But then, suddenly, you feel it. A presence overflowing with power, RIGHT BEHIND YOU. You don't have to turn around to know who that is, the pressure of it's strength crushing down on you like a boulder. What were you even thinking?! Coming here to face this monster ALONE, was the stupidest idea you've ever got and now both your team and yourself will die! As you're kneeling there, paralyzed with fear, you "hear" unsettlingly calm voice inside your head:

Stand up and turn around, human.

You swallow and slowly follow the order, tho you don't dare to look it in the eyes. The moment you do, Mewtwo just slightly flicks it's finger and all the poke balls containing the rest of your team fly out of your pockets and float above you, just beyond your reach.

Look at me.

You look up, it's piercing purple eyes stare down deep into your soul.

When they glow slightly, you feel a soft tingling in your temples and you're unable to look away. Mewtwo stares you down for around 10 minutes, then it finally closes it's eyes to seemingly to deeply think about something. After what feels like eternity, it finally speaks telepathically again:

You're different... human.

The voice surpisingly less intimidating now.

Unlike most of those i've witnessed, you don't seem to treat your Pokemon as mere pets, or battle machines...

It stops again, as if to triple check it's own intentions. Then it opens it's eyes once again, still narrowed, but somehow softer.

I have a proposition.

You nod slightly and Mewtwo continues:

In exchange for calm shelter, food, care and promise of not keeping me in a poke ball, unless absolutely necessary... I offer you my protection, loyality and promise not to harm any of your kind... except certain group.

Mewtwo slowly and hesitantly offers it's hand, already giving a lot of effort to show this shred of trust.

And DO NOT question my motives. I can always change my mind.