Why did he say "you are my bone and flesh?"
Kol Eliyahu, Divrei Eliyahu 1 (Bereishis 29:14): A baby's bones are due to his father; his flesh is due to his mother. I am like you from both sides of my ancestry; also Rus was from Kahal Hashem, unlike Do'eg's claim.
Malbim: Do not fear to return him to his kingship, lest he punish Ziknei Yehudah for rebelling against him. You need not fear punishment, for you are from his Shevet.
The Vilna Gaon explained that this is why Bnei Yisrael said so to David (Divrei ha'Yamim I, 11:1); Lavan said so to Yakov, for both Yakov's father and mother were related to Lavan.
Why does it mention being last to return the king again? Verse 12 already said so!
Malbim: Verse 12 discusses returning him to his house; our verse discusses returning him to his kingship. He intentionally mentioned first returning him to his house, as if the only question was about this. It is farfetched that there be doubt about returning him to his kingship.
