Bernese Mountain Dogs were bred to work alongside Swiss farming families, and that history shows: they are strong, willing and profoundly people-oriented. A Berner does not want to patrol the garden alone. A Berner wants to be wherever you are.
They are also sensitive. Harsh correction lands much harder on a Berner than on many breeds, and a dog who feels unfairly treated will withdraw rather than argue. Gentle, consistent training brings out the best in them quickly.
With children they are famously patient, tolerating noise and commotion with a kind of good-humoured resignation. Their size is the thing to manage rather than their nature, so teach a calm greeting early.
The trade-off for such devotion is that Berners struggle with long hours alone. If your household is empty from morning to evening most days, this is an honest reason to consider a different breed.