Margaret has Stephen elected as archbishop of Palermo, the highest ecclesiastic office in the land, in 1167.

He is ordained by Romuald, Archbishop of Salerno, only days before his elevation and it deeply rankles the old noblesse.

Romulad and Richard Palmer, bishop of Syracuse, both candidates for the vacant see of Palermo themselves, are strongly opposed, but Stephen's greatest opponent is Matthew of Ajello, a notary whom he had offended the year previous.

Stephen goes so far as to try and seize Matthew's mail, but nothing indicating conspiracy is ever proven against the notary.

Stephen is never consecrated, perhaps because had not attained the canonical age of thirty.

In this year as well, Henry, Count of Montescaglioso, the queen's brother, returns from the peninsula on the counsel of his friends, who had goaded him into making a complaint to his sister about the rank of Stephen.

Stephen wins Henry over, for a while, but rumors of an affair between Stephen and Margaret is enough to push him into a conspiracy.

Most of the Muslim staff of the palace and the eunuchs are involved in the plots and, …

…on December 15, Stephen promptly moves the court to Messina, whither he has implored his cousin Gilbert, Count of Gravina, to go with an army.

The plotters, led by Matthew of Ajello and Gentile, Bishop of Agrigento, go to Messina, but Henry, for reasons unknown, gives them up to a local judge.

At a meeting of the entire court, Gilbert accuses Henry of treason and the latter is imprisoned in Reggio Calabria.

By allowing Matthew to go free, however, Stephen has prepared the way for future plots against his life.

The Sicilian chancellor-archbishop Stephen du Perche and his entourage, including the king, William II, and queen regent, arrive in March 1168 in Palermo, where the conspirators have already arrived.

This time, Stephen’s primary opponent, the notary Matthew of Ajello, is imprisoned and Gentile, Bishop of Agrigento, flees.

He is arrested in Agrigento.

However, although the Arabs of Palermo have been soothed, …

…the Messinan Greeks have been riled by the past months and a rebellion consequently breaks out in that city (on account of the criminal practices of one of Stephen's friends, Odo Quarrel).

Here, a mob commandeers some ships and sails to Reggio, there to force the release of Henry, Count of Montescaglioso, the queen's brother.

After Henry's arrival in Messina, Odo is arrested and brutally executed and all the Frenchman of the city massacred: an inglorious prelude to the more widespread Sicilian Vespers of 1282.

Stephen prepares an army (largely of Lombards from the region of Etna) and is ready to march on Messina when the young king postpones the campaign on astrological grounds.

Matthew of Ajello, from prison, had organized the rebellion in Palermo and, seeing his opportunity, strikes.

The chancellor-archbishop is forced to take refuge in the campanile, where he holds out until offered terms.

In return for his safety, he agrees to embark at once for the Holy Land.

He is deposed as archbishop and Walter of the Mill is elected to replace him.

Gilbert of Gravina and his family are forced to do the same and they all leave for the Kingdom of Jerusalem.

Stephen, arriving in Jerusalem the summer of 1169, will soon fall ill and die.