(Answering Selene's question)
To defeat the very first Werewolves, a dangerous and infectious breed, created from Marcus's own flesh and blood: his twin brother, William. But these weren't the Lycans we know. (To Michael) Disgusting though your brethren may be, they at least have evolved. No, these were raging monsters, never able to take Human form again. It was only these later generations that learned to channel their rage. And William's appetite for destruction and rampage was insatiable. He had to be stopped. And so once Viktor's army was turned... the legions of Vampires under his control... tracked down and destroyed the animals... then captured William... and locked him away. Viktor's prisoner for all time.