Suppose there is a runner on first.
The batter hits a fly ball, and runs to first. The runner on first, anticipating that the ball will be caught, "barely" leaves first, with the expectation of returning there. The ball is caught but the batter has touched first base in the meantime.
Can the runner on first return there or is he out because the batter touched first base? Should the batter refrain from touching first base until the ball hits the ground?
(My understanding is that the runner on first is out if the batter BYpasses him on the way to second, but this is a slightly different situation.)