Sometimes, non-striking batsmen have an uncanny ability to stay in the line of sight between striking batsman and a fielder. Can they be requested to move away, and should they indeed move upon such a request?
Before the ball is struck by the batter on strike, the non-striker can stand where they like, restricted only by the limits to how far they can 'back up' and being prohibited from running or standing on the centre strip of the pitch. In practice, batters pretty much all stand in the same place and it is up to the fielders to adjust their position if they feel blocked. There is no obligation on the batter to move for a fielder.
However, once the ball has been struck both batsmen need to be careful not to obstruct the field. There are lots of grey areas in this part of the laws and it is a constant source of controversy at all levels of cricket.