The beast will ascend out of the bottomless pit:

Revelation 11:7 And when they shall have finished their testimony, the beast that ascendeth out of the bottomless pit shall make war against them, and shall overcome them, and kill them.

Revelation 17:8 The beast that thou sawest was, and is not; and shall ascend out of the bottomless pit, and go into perdition: and they that dwell on the earth shall wonder, whose names were not written in the book of life from the foundation of the world, when they behold the beast that was, and is not, and yet is.

How did he get in there, in the first place?

When was he put in there?

Is he the angel of the bottomless pit?

Revelation 9:11 And they had a king over them, which is the angel of the bottomless pit, whose name in the Hebrew tongue is Abaddon, but in the Greek tongue hath his name Apollyon.

If so, was it at the same time that Peter referred to?

II Peter 2:4 For if God spared not the angels that sinned, but cast them down to hell, and delivered them into chains of darkness, to be reserved unto judgment;

When the bottomless pit is opened, is that when he comes out?

Revelation 9:1 And the fifth angel sounded, and I saw a star fall from heaven unto the earth: and to him was given the key of the bottomless pit.

  2 And he opened the bottomless pit; and there arose a smoke out of the pit, as the smoke of a great furnace; and the sun and the air were darkened by reason of the smoke of the pit.

Was the beast's going into, and coming up out of, the bottomless pit, pictured, prophetically, in Jeremiah, in the fist half of this line?

Jeremiah 48:44a He that fleeth from the fear shall fall into the pit; and he that getteth up out of the pit shall be taken in the snare:

Also, was the beast's going into, and then coming up out of, the bottomless pit, prefiguring what happens later, to the devil?

Revelation 20:1 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand.

  2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,

  3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.

  7 And when the thousand years are expired, Satan shall be loosed out of his prison,