My idea for the story: (or rather, what should happen next, I just don't know if I'll find the time to animate it XD) Robin meets Echo by running away from his bully of an older brother and actually runs into Echo doing whatever you feel is in character for her. And they become friends. You just have fun with it though. :)
Have fun with it ;) @Pixelpocketpaws! Sorry it's so short I just don't think I'll find the time to do much else at the moment.