go native

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb idiomatic To adopt the lifestyle or outlook of local inhabitants, especially when dwelling in a colonial region; to become less refined under the influence of a less cultured, more primitive, or simpler social environment.
• verb idiomatic Of a contractor or consultant, to begin working directly as an employee for a company and cease to work through a contracting firm or agency.