Did only Yehoram see that it is Yehu?
Malbim: Yes. He saw him from afar, and Achazyahu stayed even further away 1 . This is why he needed to call to Achazyahu to flee (verse 23).
Alternatively, we could say that Yehoram recognized Yehu, who was an officer of Malchus Yisrael; Achazyahu, of Yehudah, did not recognize him. (PF)
Why did he say "ha'Shalom Ad Zenunei"?
Radak: Shalom is not proper for the evil of your mother 1 - not for her, and not for you.
Perhaps "Zenunei" hints that Izevel was a Nochris (refer to 9:22:2:1*), so Achav had no Kidushin with her; Yehoram was born from Zenus. Or, Yehu suggested that Izevel conceived Yehoram via Zenus with another man. Rashi (Sanhedrin 39b) - Achav's nature was cold; he did not enjoy Bi'ah. (PF)
Erchei Tana'im v'Amora'im (Yakov Ish Kefar Nevoriya): If Izevel was Yehoram's mother, why is he called Ben Achav? She was a Nochris idolater; surely she did not convert k'Halachah. If so, Yehoram was a Nochri, not Halachically related to Achav! (Tosfos Yevamos 16b DH Oved holds that some hold that the child is Jewish. Surely the Halachah is unlike this. Perhaps he is called Ben Achav for he was his biological son, and due to this he became king! - PF)
