Pictured on your left is an example of the butterfly known to the scientific world as Vanessa indica. In the United States this butterfly is known as the Asian Admiral, while in other parts of the world folks sometimes call this insect the Indian Red Admiral. I noticed the butterfly while watering some plants, and it cheerfully cooperated while I went inside to fetch my camera from atop a piece of my home office furniture.
I am a million miles away from being a lepidopterologist, and I found the website Butterflies and Moths of North America to be very user-friendly and informative in my quest to identify this butterfly. Once I narrowed down the search to butterflies in the general popular category of "Red Admiral," I could then determine which of these butterflies my friend really was.
Update: Upon further research I think that this variety of Red Admiral is actually Vanessa atalanta. The telling piece of evidence for my opinion is the presence of the four small triangular markings at the base of the butterfly's hindwings.