"Despite me trying to convince Sirus to return to Firenze where I could keep him safe, he insisted on staying in Roma. He told me that he was intercepting Crow messengers and assured me that neither Cesare nor the Crows were aware of his involvement with the Brotherhood. It was several months later that Sirus wrote me a letter claiming that he now knows where Il Corvo is hiding and I should assign an Assassin to help him gather more information. I did as he requested."
The Assassin arrived to Roma where Sirus tasked him to intercept one of the Crow messengers and take a very important letter from him. The Assassin killed the messenger and met with Sirus inside the courtyard of the Castel Sant'Angelo. Sirus took the letter and then told the Assassin to stay low until he finds the exact house where the Crows are hiding. It so happened that the Assassin I had sent to Sirus was the same Assassin who saw him talk with the Crow Leader back at the camp near the Colosseo. Being a suspicious man, the Assassin decided to follow Sirus.
It is possible that Sirus knew the Assassin was going to follow him; as he acted very cautiously while leaving the Castel Sant'Agelo[sic]. The Assassin's suspicion turned out to be true when in a small alcove, he was ambushed by several Crow Leaders. Sirus watches as the Assassin struggles to defend himself from the blows of the Crows. When he realized that they were losing the fight he yelled: "My Crows will do to you exactly the same as what you did to my son! You and all your brothers will pay with blood!" and fled the scene.
The Assassins killed the Crow Leaders and followed Sirus for a while but then he lost his trace.
"Sirus is Il Corvo. How could I not see through his disguise? He tricked me believing he is an ally, and yet he helped the Brotherhood on so many occasions. What was his motivation? What about the death of his son? Why is he blaming the Brotherhood for that? So many questions and there is no one who can answer them."