Vincent's answer came as a big surprise to Quinn. In the first place, the Vampire Lord had a theory about how to turn a vampire back to a human, only he wasn't quite sure if he could do it himself.
One of the possible ways Quinn had theorised, was by using a combination of the second and third stage of Qi he had recently learned. He got the idea from the time when the infection had nearly spread to Chris, Quinn's Qi teacher, before he had found out that he was actually a high ranking member of Pure.
However, rather than becoming infected and transforming into a vampire, like what had happened to Leo, instead Chris had been able to isolate and then remove the infection from his body. Now that the Vampire Lord was more proficient in Qi usage, he realised that the Pure agent must have used a combination between the second stage and third stage to do this.
At the time, Chris had even expressed that perhaps there might be a way for him to completely remove this energy from Quinn.