Immediately after his First Death, Stefan was found by the Immortal, Artemus Lowe. Lowe became his mentor, and was like a father to him. He taught Collier all he knew, and ordered his life. Lowe didn't notice that Stefan began to develop great ambition: he wanted to win The Game. The first thing he did was to behead his teacher. Lowe was completely surprised, and lost his head and Quickening to his pupil. Collier then developed a list of Immortals based on relevant calculations. Collier hunted adhering strictly to this list until 1998, when he met Amanda.
Hunt for AmandaEdit
When Amanda came to the top of Stefan's list, he tracked her down in France. But Amanda had already left the circus she had been working in. Stefan lost her trail for some years. As Amanda was the next name on his list, he felt he had to kill her before he could go on to the next name, and so stalled for years, because to move on would disrupt his calculations.
He managed to track her down again in 1998, and challenged her to fight him. When Amanda realized that he really was as good as he claimed, she fled. Stefan found her again one night near the Romanian Embassy. He almost beheaded her, but in the last moment he was shot by Nick Wolfe. Stefan revived, and restarted his search for Amanda. In the end, Amanda, tired of running, stood her ground and took his challenge. They fought, and Stefan lost his head and his Quickening to Amanda.
One of his quirks were using three Qigong balls that he had always ready to relax himself.