Reputation
William of Tyre, one of the main sources of the 12th-century, despised Joscelin, and contrasted his behavior with his predecessors, Baldwin II and Joscelin I. In his thirteenth book, William provides a character portrait of Joscelin:
The mother of Joscelin the Younger was a sister of Leo the Armenian, a very influential man among his own people. Though small of stature, Joscelin was stout of limb and very robust. His skin and hair were dark, his face broad and covered with scars from the disease called smallpox. He had bulging eyes and a prominent nose. Although of a generous disposition and distinguished for military prowess, he was yet given to excessive revelry and drunkenness. He was devoted to licentiousness and uncleanness of the flesh to the point of infamous notoriety.
According to William, Joscelin lived in Turbessel due to a lack of responsibility for Edessa and a preference for pleasure. Tyre commented that "through his lack of energy and in punishment for his sins, this Joscelin lost the entire land over which his father ruled so ably." In retelling Joscelin's final fate, he elaborated on his character. According to William, Joscelin was lazy and idle, who was "given over to low and dissolute pleasures, one who spurned good ways and followed base pursuits." William remarked that, in his rivalry with Raymond of Poitiers, Joscelin "paid but slight attention to the truth of the saying, 'When your neighbor’s house is burning, your own property is in danger.'" Armenian sources were no less forgiving. According to Michael the Syrian, he was a tyrant who joined a cult of demons. Steven Runciman gives a fairly similar character portrait, but did not mention Joscelin's distinction for military prowess:
Joscelin II of Edessa lacked his father's energy and political sense. He was an unattractive figure. He was short and thick-set, dark-haired and dark-skinned; his face was pock-marked, with a huge nose and prominent eyes. He was capable of generous gestures, but was lazy, luxurious and lascivious, and quite unfitted to command the chief outpost of Frankish Christendom.
20th-century historians generally followed this line of thinking, with some nuances. Robert Lawrence Nicholson's monograph on Joscelin III accused Joscelin II of being shortsighted, isolationist, drunken, slothful, "blind to vital matters of security", preferring the pleasure of Turbessel over defending Edessa, altogether painting a negative picture. Nicholson did comment on Joscelin II's effort to stay "loyal to his Christian faith" despite "punishments, threats, and blandishments designed to make him a convert to Islam until his death in May, 1159." Other historians like Joshua Prawer and Hans Eberhard Mayer stated that Joscelin had a "feable personality" but emphasised the structural weakness of the county over his personal faults.
More recently, William's conclusions, including those relating to Joscelin, have come under greater scrutiny. Malcolm Barber points out that while William claims that Joscelin was permanently residing at Turbessel, the Muslim historians Ibn al-Qalanisi and Ibn al-Athir believed that his residence there was temporary. Barber suggests that William's intense dislike of Joscelin III, his political rival, may have colored his portrayal of Joscelin II. In his military history of the Crusader states, Nicholas Morton believes that, not yet having lost significant territory, the county was "by no means in decline" before the fall of Edessa and could still maintain long-range offensive capacity, and that the coalition with Kara Arslan was genuinely threatening to Zengi.