Unique?
Every viva is unique – because every candidate, research project and thesis are unique.
Every viva follows expectations – because there are regulations, academic processes and culture that inform the behaviour, actions and responses of examiners and candidates.
It’s possible to hold on to both of these ideas and embrace the tension that exists between them both.
Your viva will be unique and you won’t know some of what will happen until it does AND your viva will follow the pattern of many others that have come before.