Because Viktor is a controlling bastard. He manipulates and controls people by manipulating and controlling information. Same way he lies to Selena to keep her under his control, same way he had lied and manipulated Marcus as well. In Evolution, we learn that Viktor banished Tanis due to the history Tanis was recording. We know its factual, but with Tanis gone, Viktor can change history.

>**Selene:** Andreas Tanis. He was the official historian of the Covens. He fell from favor after documenting what Viktor considered ***”malicious lies”***. Of course, as it turns out, he was probably telling the truth.

Very few immortals in the modern day are old enough to know the truth. Viktor, Kraven, Tanis, Marcus (arguably William as well), Lucian, Raze, and Amelia, the warrior turned princess who is killed on the train.