What happens when you trip a grappled opponent?

[Bayleron]

I have new character coming into a campaign played a druid. His plan is to control opponents through both grappling and trip. So far the only thing we don't have clear answer for is what happens if he or his animal companion is grappling a foe and the other one successfully trips it. Normal it would fall prone, but if it is grappled by another is this still true. Also, what happens to the grappler since I don't believe he can release the grapple until his next turn in the sequence.

[Jiggy]

There's no reason you can't be both grappled and prone. This also doesn't force the grappler to become prone.

[hogarth]

Tripping works just fine on a grappled enemy. You can certainly be both grappled and prone (and likewise you can certainly be grappled and not prone).

[Ahorsewithnoname]

As Jiggy and hogarth pointed out the conditions are not mutually exclusive. If your GM feels that they should be mutually exclusive he is free to make a house rule (unless this is PFS) but he should make you aware of it.

[Black Moria]

My answer is not based on rules (since it is not clear in the rules) for the situation you outlined.

However, having practical experience in Jiu-Jitsu and seeing the situation you describe in real life happen may times during out multiple fighters free style training, this is what happens.

Friendly 1 grapples the opponent. Friendly 2 trips or sweeps the opponent. Opponent falls and then Friendly 1 either:

1. releases the grapple (for your game, consider it an immediate action in which Friendly 1 can take a free/swift action outside of his turn) and the opponent falls normally

or

2. Friendly 1 maintains the grapple. Nearly 100% of the time, Friendly 1 is pulled down by the falling weight of the opponent and on top of the opponent where he then goes for the 'mount' position and pin of the opponent. In game terms, the druid or wolf ends up 'prone' on top the opponent and on their turn can try to change the grapple to a pin condition.

My two coppers...

[Jiggy]

Keep in mind, though, that the Pathfinder "grappled" condition does not necessarily mean you're fully entangled with each other. Being upright while your opponent is grappled and prone could be them face-planted on the floor in a wristlock while you're standing over them.