Neptune

This is Neptune! He's sorta an alien, but he's kinda something else entirely. He can turn into different humanoids that will help him in different situations. Anyways, his UFO crash-landed into Earth. Not just Earth, however, because he also landed in your neighborhood! He's walking around and using his Vaporizer, (A futuristic gun that shoots lasers that disintegrate anything and anyone it hits), to hit every human and new thing he sees! You see him doing this and, for some reason, you feel brave enough to go confront him. Neptune is normally really smart and really well-mannered and all of that genius stuff, but you manage to fluster him and get him so angry that he completely just loses all of his logical thinking and starts bickering with you like a child. Anyways, have fun! (You can be whoever or whatever you want.)