What color should i paint one white wall in my bedroom my bedroom is purple and has butterflies all over it?

An accent wall in a celery green would like great in your room, as long as you like green.

You could use a soft lavender or pink to enhance the purple and make the room very feminine.

A butter yellow will make the room feel sunny, eve if you do not have a lot of Windows.

And a soft to medium blue will open the room up, as if the sky were visible trough the wall.

Let you personal taste guide you in your choice.