Some TMNT stuff really isn't for little kids.
Lucius Fox is a high ranking member of the board at Wayne Enterprises and a major ally of Bruce Wayne.
After Batman acquired one of Raphael's sai in a fight, he enlisted Lucius Fox to analyze the weapon. Fox soon discovered that the weapon—and the Turtles as well—are from a parallel universe, which had previously been the speculative domain of Doctor Naveen Khan, who had begun the construction of a trans-dimensional portal.
Fox also analyzed a small amount of blood on the sai, discovering that it was infused with mutagen, and that the mutagen's effects—as a result of being in a foreign universe—were beginning to wear off. With this information, Batman took his leave of Fox.