Zedekiah was probably not the strongest personality. He asked for Jeremiah to pray for Jerusalem, perhaps in the hope God would save them:
Jeremiah 37:2 But neither King Zedekiah nor his attendants nor the people who were left in the land listened to what the Lord said through Jeremiah.
In contrast, when Zedekiah’s officials wanted to kill Jeremiah, Zedekiah did not have the power to stop them, but he did have the power to send another official to rescue the prophet, later promising in secret to protect Jeremiah from the men who wanted him dead.
Did Zedekiah fear men more than God? On being told to surrender to Babylon, so he could live, Zedekiah told Jeremiah:
Jeremiah 38:19 But I am afraid to surrender … for the Babylonians may hand me over to the Judeans who have defected to them. And who knows what they will do to me!