Then in haste every man of them took his garment and put it under him on the bare steps, and they blew the trumpet and proclaimed, “Jehu is king.”
2 Kings 9:13

As soon as King Joram's men heard that Jehu had been anointed as the new king of Israel, they switched sides. The same happened with both of Joram's messengers in vs 18-19 and with Jezebel's eunuchs in v32.

Tyrants have no real friends, only sycophants who will turn on their masters the moment the winds shift.