When do you receive a bonus action and reaction?

Question

When you start combat, after determining surprise and establishing positions; you roll for initiative. At this point, do all combatants have a reaction or bonus action even if they are not first?

For example: "X" is talking to "Y" when they break out in a fight. The fight begins with X and Y standing adjacent to one another. X is first in the initiative order and decides to move away then attack. Does Y have the ability to use a reaction (Attack of Opportunity)? If yes, can he use another reaction after his turn?

In a sense I am asking if reactions can be used on a per round basis or specific to the character.

If it were a per round basis, Y could perform an Attack of opportunity and on his turn will not be able to ready an action.

If it is specific, he won't be able to perform an Attack of Opportunity on X's turn, but would be able to if he moves so he is adjacent to X and X moves away on his turn.

Or can Y use a reaction to attack, then on his turn, gains back a reaction?

Answer 1

Short answer: Yes, you can take a reaction before your first turn in combat.

Reactions and bonus actions aren't ever something you “have”, they're something you do. And there is a limit on the number of times in a round that you can do them.

As a consequence, it doesn't make sense to ask if you “have” either one when you are surprised. What matters is whether you can do things that count as a reaction or as a bonus action. The only reason you wouldn't be able to take a reaction before your first turn is if you're surprised (both quotes from PHB page 189):

Surprise

If you’re surprised, you can’t move or take an action on your first turn of the combat, and you can’t take a reaction until that turn ends.

Bonus Actions

[…] anything that deprives you of your ability to take actions also prevents you from taking a bonus action.

So since you're not surprised in this scenario, you can still take reactions.

Also note that surprise also doesn't occur just because you lose initiative. To be surprised:

character or monster that doesn’t notice a threat is surprised at the start of the encounter.

If you're used to earlier editions of D&D that have a “flat-footed” rule that make you vulnerable in a surprised-like way until your first-round initiative comes up, that might be the source of your assumption that someone can't act in 5e until the first time they have a turn in a combat. There is no similar rule in D&D 5e: if you're unsurprised, you are no more vulnerable before your first turn than after.

Answer 2

Yes. it is round based.

If you have the ability to take a Bonus Action you can only do so on your turn (unless other wise specified by the special class technique or what-have-you that grants you a bonus action.

Similarly if you have a feature that grants a Reaction, you can take it on your turn OR on someone else's turn if its a triggering effect such as the spell Shield, you get hit on the monsters turn, you use your reaction, on the monsters turn to cast shield, raising your AC by 5 and possibly negating the attack.

Its important to not that via the rules on page 189 and 190 of the PHB that you only get these actions if you have a feature, spell, item etc that grants you these actions. not every one will have the ability to do a bonus action or a reaction.

And as far as when these thing apply, immediately after you roll initiative and start combat. So in your example above, if you roll initiative and X moves away from Y, Y gets an OA. Note that Y would not get this OA if Y is surprised, as being surprised deprives you of your actions, all actions, even moving.

Answer 3

Let's deal with the question in two parts so that we cover everything.

First Round:

If you are Surprised then you don't get any actions in the first round. The obvious exception is if you have some power, magic item or whatnot that supersedes this rule. Normally you wouldn't get any Reactions (because you are surprised) not would you get a Bonus Actions (because you don't get a turn).

All Other Rounds:

You would get your Reactions in a normal round even if it isn't your initiative turn yet. The Reactions in question are still governed by whatever specific rules apply to that particular Reaction. However, you aren't Surprised or anything so you get them as normal.

Bonus Actions you would get on your turn as normal.