The Protection fighting style is described (SRD, p. 24) as:
When a creature you can see attacks a target other than you that is within 5 feet of you, you can use your reaction to impose disadvantage on the attack roll. You must be wielding a shield.
Picturing a scenario where a creature (presumably an ally) is beside you and is attacked by an enemy, the Protection fighting style is used. It raises the following questions:
- Does the reaction make the Paladin move in between the Attacker and creature you were protecting?
- Should the movement be deducted from the Paladin's available movement next turn?
- If the Paladin moves in between the two creatures, which position should it take? The attacker's (moving the attacker one tile away) or the protected creature (moving it behind the Paladin)?