Question on order of events concerning Grapple

[DM Mathpro]

One of the campaigns I'm running online here is in the middle of combat and I'm wondering how to resolve this situation. At the beginning of the round the BBEG went to attack a party member. Another party member grappled the BBEG on his way(attack of opportunity). Now does the BBEG have to spend the rest of the round grappled now or since its still the BBEG's imitative does she get a chance to break free?

[Chris P. Bacon]

Here's how I see the action order, if I'm understanding this correctly:

1. BBEG takes a move action to approach PC#1 she intends to attack.
2. This triggers an AoO from PC#2 (who apparently has the ability to grapple on an AoO; Tetori maybe?).
3. The grapple attempt is successful. The BBEG is grappled and can't move any further.
4. The BBEG still has a standard action to spend, and can spend this on an attempt to break free of the grapple if she chooses, or cast a spell, etc.

I hope that makes sense and answers your question!

[Are]

Of course, there's the fact that grappling is a standard action of its own, and can't be made as an AoO (unless you're a tetori monk, or you otherwise have grab as a special attack).

The only combat maneuvers that can normally be made as an AoO are disarm, sunder, and trip.

If one of those are used instead of grappling, the order of events is as Chris P. Bacon stated.