Jim's debt
When Quinn had lived through Vincent's life, it had started from a certain point and not the very beginning. He remembered seeing Jim briefly in those memories and from what he understood, Jim used to be one of Vincent's Vampire knights, but he had been more than that.
Technically, Jim was older then Vincent and for some reason he had always treated Vincent with great respect, despite being his uncle. When Quinn had asked Edward about it, he had unfortunately been unaware of the reason for this.
"I thought unlike other abilities that one was supposed to be the exclusive ability for the tenth family leader?" Quinn questioned, being confused as to how a Vampire knight like Jim could have gotten access to it.