Before leaving Nasir Town, Byrne went specifically to the basement to explain the situation to Irene and Chris.
"While I'm gone, the Fischer family must be cautious. The Kesse family is likely to seek revenge, as our actions have clearly humiliated them."
He knew the Kesse family's domineering style well, and with the Garcia family backing them, they were certain they could completely overpower the Fischer family.
Thus, having been fiercely slapped in the face by the Fischer family, they must brace for the possibility of retaliation.
Irene nodded with her arms crossed, her expression serious as she said, "Mm, we will keep as low a profile as possible and not leave Nasir Town. Even if we must leave, we will do so with caution and secrecy."
Chris also nodded silently.
He considered whether to assassinate key figures on the Kesse family's territory, but since Byrne and Irene had decided to act with discretion and subtlety, that plan would have to wait.