The first years of Raymond and Constance's joint rule were spent in conflicts with the Byzantine Emperor John II Comnenus, who had come south partly to recover Cilicia from Leo of Armenia, and to reassert his rights over Antioch. Raymond was forced to pay homage, and even to promise to cede his principality as soon as he was recompensed by a new fief, which John promised to carve out for him in the Muslim territory to the east of Antioch. The expedition of 1138, in which Raymond joined with John, and which was to conquer this territory, naturally proved a failure. Raymond was not anxious to help the emperor to acquire new territories, when their acquisition only meant for him the loss of Antioch. John Comnenus returned unsuccessful to Constantinople, after demanding from Raymond, without response, the surrender of the citadel of Antioch.
In the last year of Raymond's life Louis VII and his wife Eleanor of Aquitaine (Raymond's niece) visited Antioch. Raymond sought to prevent Louis from going south to Jerusalem and to induce him to stay in Antioch and help in the conquest of Aleppo and Caesarea. Raymond was also suspected of having an incestuous affair with his beautiful niece Eleanor. According to John of Salisbury, Louis became suspicious of the attention Raymond lavished on Eleanor, and the long conversations they enjoyed. William of Tyre claims that Raymond seduced Eleanor to get revenge on her husband, who refused to aid him in his wars against the Saracens, and that "contrary to [Eleanor's] royal dignity, she disregarded her marriage vows and was unfaithful to her husband." Most modern historians dismiss such rumours, however, pointing out the closeness of Raymond and his niece during her early childhood, and the effulgent Aquitainian manner of behaviour.
Louis hastily left Antioch and Raymond was balked in his plans. In 1149 he was killed in the Battle of Inab during an expedition against Nur ad-Din. He was beheaded by Shirkuh, the uncle of Saladin, and his head was placed in a silver box and sent to the Caliph of Baghdad as a gift.
Raymond is described by William of Tyre (the main authority for his career) as "a lord of noble descent, of tall and elegant figure, the handsomest of the princes of the earth, a man of charming affability and conversation, open-handed and magnificent beyond measure"; pre-eminent in the use of arms and military experience; litteratorum, licet ipse illiteratus esset, cultor ("although he was himself illiterate, he was a cultivator of literature" - he caused the Chanson des chétifs to be composed); a regular churchman and faithful husband; but headstrong, irascible and unreasonable, with too great a passion for gambling (bk. xiv. c. xxi.). For his career see Rey, in the Revue de l'orient latin, vol. iv.