Alrighty, I've spoken with the very helpful Jean over at Vivere disce, and she's said to assume it was just your average run-of-the-mill human who's caused Megan to vanish, since "people are bastards".
I spent today walking through the city, searching her usual haunts and asking random people walking past if they had seen her. no luck.
Megan, if you did just run away and if you can see this, please come home. Mum and dad are out of their minds worrying about you. If you come home I'll even give you my Majora's Mask!
Having said that, if someone has taken her, and on the very very very off chance they are reading this, then be prepared to suffer a very slow death via one of my kitchen knives <3.
(Lastly, I know this is an incredibly facebook/myspace-y thing to do, but this song perfectly describes my attitude at the moment)