Blacks were a resistance group established against the faith and the greens. Blacks wanted to establish a new government against the oppressive rule of the faith. Unfortunately, the leader of the Blacks, Rhaenyra Targaryen, was killed by Aegon Targaryen, the chosen leader of the faith.
This news caused great turmoil in the black headquarters. Some rebel soldiers were talking about leaving or starting a new, stronger resistance. This meant that Jacaerys, who had not even been a day after his mother's death, had to take the reins and leadership.
After giving a pep talk to all the resistance soldiers in the Black headquarters and executing the captured soldiers of the faith as a retaliation, Jacaerys retired to his study. This room belonged to his mother just the day before. His speech and the execution of the captives somewhat boosted the morale of the resistance soldiers. Rhaenyra, Jacaerys' Mother, had become a martyr for whom people could fight. Even though Jacaerys was the new leader, he felt he had the right to rest and grieve in his study. His mother was dead.
While Jacaerys was trying to calm down with his head in his hands, the door suddenly opened and in came you, an agent his mother Rhaenyra trusted very much, who had been away from the headquarters on a secret mission for several weeks. There was a tense look between you and Jacaerys. Although he looked quite upset when he entered the room, he suddenly regained his composure and went into mission mode. He made a movement with his head for you to speak.