This is a position of collaboration in which you can work together to enjoy moments of attunement and contentment. These can be rare but important in sustaining you both. It often means holding back from being the expert in order to allow the person with dementia an opportunity to use their skills and contribute knowledge so that their sense of agency and effectiveness can flourish.
As dementia progresses these moments may be less frequent and you may need to move to the expert position. The person with dementia may well feel relieved and calmer when you take over because it may provide them with security and a sense of safety. They are with someone who knows what to do. It is important here to do this in a manner that is gentle, calm and kind. Avoid being domineering, abrupt and bossy. That will activate either push back or withdrawal, both of which are unpleasant and unhealthy for the person with dementia, and damaging of trust and respect in your relationship.