The Expanded Universe is a wonderful place, where new ideas can frolic without having to worry about fitting into the Canon. However, sometimes an idea is so interesting that the people who create the canon decide it deserves to become real. If they're successful enough, they'll be included in new entries in the Expanded Universe, cross-pollinating concepts. Canon Immigrants are often part of an Adaptation Distillation, and new, canonical version usually has extra details to tie them into the more complex backstory of the original. This is what every Canon Foreigner strives to be.