It is possible for a ball to roll foul and then roll back into fair territory, as long as it doesn’t pass first or third base before doing so. Although this is not a common occurrence, it can happen more frequently in lower levels of baseball due to fielders’ lack of focus or reaction time.
Once a fielder touches the ball in foul territory, however, the ball is immediately considered foul. This situation often arises with bunts or dribblers along the first or third baseline, where the ball might initially roll into foul territory before returning to fair territory due to the contour of the field or other factors.
It is highly unlikely, if not impossible, for a line drive to exhibit such behavior due to the speed and trajectory of the ball. Once the ball rolls past the first or third-base bag, it remains foul even if it reenters fair territory.
Lastly, it is considered interference if someone blows on the ball to make it go foul, which can result in penalties such as awarding the batter or runner first base or an extra base.