A quote from ENDER GAME (Orson Scott Card). Very meaningful quote that I like to share it with you.
If you mimic someone's identity make sure to make it more realistic and much more believable. Make a major characters more fully than minor one.
Whilst someone take on an identity, they will start behaving someone like it. As in "COPY-PASTE", their mind and character are will adapt to the identity their trying to project.
And start becoming it.
Setting a limit on what you are going to portray is the best solution to this. But this is very dangerous. As long as you are there you have the difficulty to go out. If you have hard time to set yourself free then that is a big QUESTION.