I was watching Dice, Camera, Action and Chris Perkins had an interpretation of opportunity attacks that I wasn't sure he made to keep a character alive or it was the official rule (cause it kind of made sense). In the first round of combat, he allowed a PC to move past an enemy without an opportunity attack because the PC had higher initiative and the NPC had not yet taken an action. This seems consistent with the rules since you cannot take a reaction with first having an action occur. I didn't see any mention of this in the PHB or Xanathar's. Does anyone else use this interpretation as a rule?
It's correct. Reactions reset on your turn in initiative, so if you give someone a reaction in the first round before their turn, they essentially get a free reaction. Basically, if they have a 15 initiative, they get 1 reaction from initiative 15 in round 1 to initiative 15 in round 2 and so on.
It's also supported by the surprise mechanics, where a surprised creature can't take an action on their first turn, and can't take reactions until their first turn ends.
AFAIK, you always can take a reaction unless you're surprised, even if you haven't taken a turn in combat yet. For example, if you were fighting a horde of monsters (that you clearly saw coming from a large distance away), it wouldn't make sense to not be able to take a reaction in the first round, even before you've gone.
There is no rule that says you cannot take a reaction before an action.
Unless the enemy in this story was surprised, then that enemy should have been able to make an attack of opportunity (barring the PC having a feat like Mobile or disengaging or otherwise doing something that prevents AoO).
You can take your reaction before your first turn unless you are surprised. Thus is supported by surprise mechanics since you can use your reaction after your first turn, even though you can't take actions that turn.
The reaction rules don't say anything about a first turn exception, and if you couldn't take a reaction until after your first turn, there would be no need for surprised to state that you cannot use reactions until your surprise turn has ended.
I was watching Dice, Camera, Action and Chris Perkins had an interpretation of opportunity attacks that I wasn't sure he made to keep a character alive or it was the official rule (cause it kind of made sense). In the first round of combat, he allowed a PC to move past an enemy without an opportunity attack because the PC had higher initiative and the NPC had not yet taken an action. This seems consistent with the rules since you cannot take a reaction with first having an action occur. I didn't see any mention of this in the PHB or Xanathar's. Does anyone else use this interpretation as a rule?
It's correct. Reactions reset on your turn in initiative, so if you give someone a reaction in the first round before their turn, they essentially get a free reaction. Basically, if they have a 15 initiative, they get 1 reaction from initiative 15 in round 1 to initiative 15 in round 2 and so on.
It's also supported by the surprise mechanics, where a surprised creature can't take an action on their first turn, and can't take reactions until their first turn ends.
AFAIK, you always can take a reaction unless you're surprised, even if you haven't taken a turn in combat yet. For example, if you were fighting a horde of monsters (that you clearly saw coming from a large distance away), it wouldn't make sense to not be able to take a reaction in the first round, even before you've gone.
There is no rule that says you cannot take a reaction before an action.
Unless the enemy in this story was surprised, then that enemy should have been able to make an attack of opportunity (barring the PC having a feat like Mobile or disengaging or otherwise doing something that prevents AoO).
You can take your reaction before your first turn unless you are surprised. Thus is supported by surprise mechanics since you can use your reaction after your first turn, even though you can't take actions that turn.
The reaction rules don't say anything about a first turn exception, and if you couldn't take a reaction until after your first turn, there would be no need for surprised to state that you cannot use reactions until your surprise turn has ended.
So I guess the creatures were surprised...
"Not all those who wander are lost"