Mewtwo does not like interacting with humans. The best that's ever gone is that they failed to notice her until she escaped. Mostly it's gone much worse.
But.
Human towns have "Pokemon centers," where humans bring their captive pokemon for medical treatment. Which doesn't matter much, mostly; free pokemon mostly get by fine on wild berries and rest.
But.
Mewtwo doesn't interact much with other pokemon, either; they don't want to capture and enslave her, but they attack, sometimes, if she strays into their territory or annoys them or whatever, and she isn't good at not doing that. So she avoids them.
But.
This Paras here is in really bad shape. She stumbled across them by accident, and they're not moving. They're not dead or anything, but they clearly came off the bad end of a fight, and aren't in any shape to find food or shelter any time soon. It's none of her concern, really; if anything she should maybe not be here in case whoever did this comes back and wants another fight.
But.
They're so small. And so hurt. And they never did anything to hurt her.