Captain Jack Harkness lands in Equestria. The entire realm goes R-rated (or worse) in short order. After all, Ponies are cute, and Jack is... well, the closest thing the Whoniverse has to an actual incubus.
Addendum: the Changeling invasion is resolved swiftly and amicably when Jack heroically volunteers to provide enough "love" for the entire species. Chrysalis bravely volunteers to be his "primary point of contact," for the sake of her people....
Addendum: the Changeling invasion is resolved swiftly and amicably when Jack heroically volunteers to provide enough "love" for the entire species. Chrysalis bravely volunteers to be his "primary point of contact," for the sake of her people....