Me, I would try to cause mayhem through pranks and also by force feeding Rainbow Dash laxatives. I would introduce the CMC to the magic that is lighting your farts on fire and I would glue inflatable woopie cushions to Celestia's throne.

Yes I know I'm a nut sometimes but it would all be in good taste right???

But that's just things I would do when I'm bored. Of coarse I would love to hang out with the main 6, but I would eventually go into the Everfree and find Chrysalis and try to convince her to let me stay in the hive as sunlight tends to frighten me sometimes.

845143
You need help.
Edit: There is the retarded insane, then there is insane.
Your are the former... I am the latter.

Mayhem all the way

845149 * Continues to stare awkwardly*

845152
I'm going to cut you!

845156

845143 I'd just want some peace and quiet.

845150>>845156>>845175

HIA !!!

845158
I'm not joking. I will slice your throat with a rusty crochet needle.

845181
What is this? I don't even...

845143That's perfect. I would help you.

845181
OmGawd! you iz so sexxay girRrl.

I would become try to become friends with the mane six and I would attempt to court Fluttershy, Twilight Sparkle, Octavia, or adult Scootaloo. THEY ARE GOING TO LOVE ME!

848922
Adult Scoots?
Why not Apple Bloom?

1022676
Why not all three of the cutie mark crusaders? I hear that herds are coming back so why not take advantage of that.

845143 I'd research and understand what they classify as magic and try to apply theoretical physics to it, if i succeed then i'll try to make a magitech fusion reactor, if not then i'll look into ways to extend my life magically as with technology things are just too cumbersome, plus there should be someway to at least rejuvenate.
Regarding interaction with the cast, i'd probably be all over Twilight and, if possible, Luna. Try to establish democratic relations with Chrysalis to pursue new magical energy sources from love or any emotion.