The Imprisoned

The Imprisoned is a black beast featured in Skyward Sword. This monster is imprisoned in the Sealed Grounds, and haunts Link's dreams in the opening of the game. Due to the seal placed in the past upon Demise by the goddess Hylia after failing to obtain the Triforce, he assumes this monstrous form throughout most of the game.

Appearance
The Imprisoned is a massive beast with three rows of teeth, and large black scales across its body. It has black flame-like spines across its back, and large four white appendages on each of its feet that resemble toes.

The first time it appears, it only has two legs. The second time it gains arms which also have white appendages and tries to climb up to the Sealed Temple. During the third battle, it has a tail and can fly by releasing a large black ring from its back which carries it through the air.

History
In the present era, Zelda uses the Gate of Time in order to return to the time where Demise was recently sealed. Entering an age-long sleep to sustain her mortal body, she managed to keep the seal intact until, thousands of years later, The Imprisoned grows strong enough to overcome it. He is driven back three times, initially by Link alone and later with Groose's help. In each instance, Link must topple The Imprisoned over and drive the sealing spike back into its forehead, and finally deliver a Skyward Strike to the spike to reset the seal.

Eventually, Link manages to acquire the complete Triforce, and wishes for the eradication of Demise. With Demise gone, Zelda awakes, since the seal she was sustaining was no longer necessary. At this point however, Ghirahim intervenes, capturing Zelda and bringing her to the past, where his master could still be revived. Despite his subsequent defeat by Link's hands, the ritual Ghirahim had begun to perform completes, restoring Demise in his previous form.

Strategy
In all three battles, the general strategy for The Imprisoned is to destroy all eight of the appendages on its feet, causing it to fall down, and then driving the spike into its head. Doing this three times will cause it to be absorbed into the spike, which Link will seal into the ground.

During the second and third battle, Link will be accompanied by Groose who has built a machine, the Groosenator, which is a rail around the pit with a cart that has a catapult which he uses to fling large bombs at The Imprisoned, temporarily stunning him. Link can use the Groosenator to prevent The Imprisoned from climbing up the slopes of the pit, and also to stun him if The Imprisoned gets too far ahead or unapproachable. When The Imprisoned takes flight, a hit from the Groosenator will knock him back down to earth. During the third battle, Groose's stash of bomb flowers will be blocked off, and he will have to fling Link onto The Imprisoned's head.

Another tactic during the second and third battle is for Link to get a level above The Imprisoned and have Groose stun him with a bomb, then jump on The Imprisoned's head and attack the spike. Doing this quickly will result in The Imprisoned beginning its next wave of attacks. However, if Link is too slow, The Imprisoned will throw him off his head and Link will have to try again, although the spike will remain in its depth. This tactic can be essential during Lanayru's Boss Challenge as Link can receive little to no damage using this tactic, and get the battle over quickly.

Theory
Interestingly, the seal upon The Imprisoned - which Link is forced to renew three times - appears to be the result of Link defeating Demise at the end of the game (this also explains why a Skyward Strike is needed to reset the seal). In this sense, the 'final' destruction of Demise does not take place at the conclusion of the game, but shortly before it, when the Triforce is used to vanquish The Imprisoned in the present era. The final battle with Demise himself has, technically, already occurred the very first time Link faces the Imprisoned and must renew the seal.

Trivia

 * The Imprisoned's new traits after each "defeat," possibly foreshadow his true form, taking on the shapes they do as a result of his demonic disfigurement. While the arms might merely resemble his actual arms, his tail could indicate his trailing kilt while the halo he sprouts might further represent his fiery mane with its red accent.
 * The Imprisoned's physical form might be explained by the very nature in which it is imprisoned. Forced underground, and possibly into the sealing spike itself, it is rendered physically blind.  Knowing nothing more than an insatiable appetite for power and destruction, as well as a soul to assume its original form, its body is little more than a walking mouth.  This inclination is best illustrated as it devours Zelda's soul within Hylia's Realm in the past.
 * Its flaming mane seems to indicate its state of being. Upon its transformation into Demise, the mane remains black for a mere moment until Demise stands erect.  After he's composed, it ignites and glows like fire.  The blackened shade it formerly has would then indicate his dormancy.