I would befriend it no matter what. Despite what kind it is, classic, shapeshifting, Asian, European, whatever.
Whatever knowledge they had, I'd take it. All of their magic, their tactics, everything-- I'd be their greatest student.
Though, my main concern would be uniting humans and dragons. I mean, obviously not ALL of humanity would be up to it, but seriously, that'd give us a KICK ASS army to fight the aliens with. And it's better than humans fighting dragons. They'd kick OUR asses.
My only concern would be us, being our stupid, violent selves, using the dragons to fight EACH OTHER. Then the aliens would just laugh at us.