Although Holden resented Sean and Rose, he knew that Sean was right. He had already experienced how vicious and mighty his elder twin brother was when Holden was on Star Island. Star Island was not huge or developed, and Harry’s defense measures were not very good. However, Holden did a very good job.
Even so, Holden was not able to defend Sebastian from conquering the city. It only took three days for Sebastian to take over the entire Star Island. After that, Holden found out that the reason