1 Kings 1:24-25

1 Kings 1:24-25King James Version (KJV)
24 And Nathan said, My lord, O king, hast thou said, Adonijah shall reign after me, and he shall sit upon my throne?
25 For he is gone down this day, and hath slain oxen and fat cattle and sheep in abundance, and hath called all the king's sons, and the captains of the host, and Abiathar the priest; and, behold, they eat and drink before him, and say, God save king Adonijah.
American English Bible
24 And he said: 'My lord; O king; Did you say that AdoniJah will reign after you and sit on your throne? 25 For today he has gone to sacrifice many calves, lambs, and sheep, and he has invited all your sons, the chiefs of the army, and AbiAthar the Priest. Why look! They're eating and drinking before him now, and saying, Long live King AdoniJah!

These are my thoughts, please share yours.
24 Nathan respected that David was still king this also shows that God still viewed David as the rightful king because His prophet called him king. This was a rhetorical question; both David and Nathan knew the answer to the question. David would be wondering why he was asking this though. The throne normally would go to the oldest but God works His own way and those that follow Him do as well.
25 This is a retelling of what scripture says earlier in the chapter and this is the second time David has heard this. Scripture is not clear on if he heard it back to back or there was time between hearing this news but, he was to react, this was God’s plans. This was a big treat because these people already saw Adonijah as king and David had to reunite the kingdom.