Grappling rules confusing? Never!
I think Rules-wise, it is possible for one of us to Grapple Chrysagon (helped by another?), and then move him. If we move him out of the reach of the vine, then its grapple would break. With that reach it may take two turns (since movement would be halved). In the intervening turn for the vine, though, it would attack and do damage, and perhaps draw the player back to it.
Would the rescuer(s) have a strength test with the vine? I don't know.
I think Rules-wise, it is possible for one of us to Grapple Chrysagon (helped by another?), and then move him. If we move him out of the reach of the vine, then its grapple would break. With that reach it may take two turns (since movement would be halved). In the intervening turn for the vine, though, it would attack and do damage, and perhaps draw the player back to it.
Would the rescuer(s) have a strength test with the vine? I don't know.