Uriel was cornered from all possible perspectives. He was in a hostile place filled with an uncanny amount of malevolent flux energy, in the presence of a foul creature that knew nothing but hunger and the two most powerful members of the society. Going by this it would have been easy to assume his defeat was the inevitable outcome yet when Mark saw a grin appear on the young archaeologist's face he knew he made the right decision by coming back to help him.
From the moment Mark saw the creature they summoned he realized escaping the dungeon would mean surviving only for a short period of time. A creature so powerful could not be controlled by any of the means at their disposal and it was only a matter of time until the creature killed him or even worse, until the government got involved and dispatched holy rank hunters to capture him for being involved with the group responsible for summoning it.