Does this character sound like a Mary Sue?

No, the qualities of the guides seem pretty clever. I especially like the lazy eye thing, and the fact that they don't care about gender, very unique. And anyway, how you write the story dictates whether the character is a Mary Sue or not. Also, I have one suggestion, when I was reading Laughlin's description I kinda of imagined him/her being a little bit mischievous, you said they were easily amused so.....just a thought. It sounds great so far, good luck :D