Marvin: “Who are you, strange creature?”
Pinkie: “Hehehe, hi!! I’m Pinkie Pie!! And I’m an earth pony who wants to be your friend!! Who are you? Are you some kind of a Trojan from outer space?
Marvin: “Something like that. I am Marvin the Martian from the planet Mars and I’m here to blow up the Earth into dust. Did you say you’re an…Earth…pony?” (Hmm…I shall capture that Earth pony creature and add it to my collection)
Pinkie: “Yes indeedy… HOLD ON!! You said you want to blow up the Earth?!! Oh-no-no-no-no!!! Bad idea. My friends live on that planet. YOU CAN’T DO THAT!!”
Marvin: “I can and I will, just watch me.”
Pinkie: “But you’ll kill my friends!! I won’t let you!! (I’ve got to stop him)”

If they fight Marvin will lose. If they team up we all lose.