End of Adventure Boss: "I grapple, then start flying up...I keep flying up....I keep flying up..." Meanwhile, if the boss can't get out of the grapple within the first couple rounds, he's pretty much screwed.
Naw, if a lone enemy gets grappled for several rounds against a team their a goner. Aspects will start to build and it will quickly become impossible to break the grapple. Then other PC's join the fun, the aspects spiral out of control, and the baddie dies.
Consider the following scenario: Due to a hilariously large number of fate points being spent, the shagnasty gets grappled by 6 squirrels.
Round 1: Shagnasty can't do anything to to the large blocks from a fate point spam.
Round 2: The shagnasty gets 6 aspects placed on it. Which ever squirrel rolled well tags a few of the aspects to get a block of lots. Shagnasty can't break free.
Round 3+: The aspects start to build up and up until the squirrels have a nice pile of backup tags.
Final round: Squirrels switch to stress, and tag to increase the stress to an absurd level. The shagnasty is finally gnawed to death. Also very upset that it was defeated by a pack of squirrels.