Who is the protagonist?
The protagonist is usually the character who enters from the outside and either disrupts or threatens to disrupt the status quo. For example, Blanche Du Bois in A Streetcar Named Desire moves into the small apartment with her sister Stella and her brother-in-law Stanley Kowalski. It is Blanche who changes the status quo in the little world by creating discord between Stella and Stanley. The protagonist is always the most conspicuous in plays. In The Odd Couple it is Felix Ungar who moves into Oscar Madison's apartment and immediately starts disrupting the status quo--albeit that the status quo is a mess. Oscar is a slob. Felix is a neat freak who wants to organize everything. Oscar is essentially an easygoing guy who puts up with Felix, but the conflict is based on Felix's efforts to change everything and Oscar's resistance to change. There is no doubt that Felix Ungar is the protagonist.