It’s important you can discuss the slipperiness of language. Feste, in particular, represents the idea of language which can be manipulated.

Feste describes his role in Olivia's household, I am indeed not her   but her   of words (III.1.29–30).

Ask yourself: Does Feste’s role as Olivia’s ‘fool’ mean he has more freedom to speak his mind and criticise her, or less?