"To inhabit the character" means fully immersing oneself in the role or personality of a fictional character. It involves understanding their thoughts, emotions, and behaviors in order to portray them convincingly. Full definition
Films like J. Edgar and The Aviator (for which he got a Leading Role nomination) require him to play a single character through many stages of his life, never allowing the actor to fully inhabit characters at a single point in time. (businessinsider.com)
For Variety «s «Actors on Actors,» Hong Chau and Diane Kruger sat down to talk about inhabiting characters who've experienced loss, feeling like they're meant for a particular role, and more. (variety.com)
Thank you for volunteering for the Games and inhabiting these characters with such texture, color, humor and pain,» she said. (justjared.com)