John Gill Commentary 2 Kings 10:13

"Jehu met with the brethren of Ahaziah king of Judah, and said, Who are ye? And they answered, We are the brethren of Ahaziah: and we go down to salute the children of the king and the children of the queen." — 2 Kings 10:13 (ASV)

Jehu met with the brethren of Ahaziah king of Judah
At the above place; these were the sons of his brethren, called his brethren, as Lot was called Abraham's brother, being his brother's son; for as for his brethren, they had been slain by the Arabians before he was made king, (2 Chronicles 22:1 2 Chronicles 22:8) ,

and said, who are you ?
though perhaps he knew who they were:

and they answered, we are the brethren of Ahaziah ;
the sons of his brethren:

and we go down to salute the children of the king, and the children of
the queen ;
meaning either the children of Ahab and Jezebel, or of Joram and his queen; for they knew nothing of the death of Joram and Jezebel, and the revolution made in the kingdom, and therefore with great simplicity tell who they were, and where they were going, and on what account.