[Your soulbound Sirius has used Samael's Domain.]
Adrian made Sirius use his domain when the attention was all changed to Charon upon using the latter's domain. The red area of Hell also made it quite easy to hide the reddish mist and color palette change when Sirius uses his own domain. Upon using the domain, Adrian immediately commanded Sirius to create illusions of him in his current area.
When the illusion of Adrian has been set, he immediately teleported above the Hell Beast as he needed a closer look on the runes engraved on it. From the eyes of those that do not have a skill that can differentiate reality from illusion, it looked like Adrian was struggling against his attacker. In reality, the female Follower of the Distorted God is being rooted by Sirius' shadows.