Immediately after his first death, Stefan was found by the Immortal Artemis Lowe. Lowe became his mentor and was like a father to him. He teached him all he knew and ordered his life. Lowe didn't notice that Stefan began to develop great ambition: he wanted to go ahead in The Game. The first thing he found obvious to do was to behead his teacher. Lowe was completely suprized, and lost his head and Quickening to his pupil. After that he developed a list of Immortals. His list was based on relevant calculations and astrological considerations. Collier kept strictly to this list and drove untill 1998 well with this tactic. One of his quirks were three Qigong balls that he had always ready to relax himself.
At some piont Amanda was the next victim on Stefan's list. He had tracked her down in France during the early 90s. But Amanda left the circus she had worked in. Stefan lost her trail for some years. As Amanda was the next on his list he had to kill her before he could go on. He managed to track her down in the year 1998, and challenged her to fight him. When Amande realized that she was infererior to him, she fled. Stefan found her again at night by 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 was tired of running away from Stefan, and took on his challenge. They had their fight in an alley. Stefan lost and was beheaded by Amanda.