Uncle MaGallan was a dad for him despite their differences.
So, when he heard that his Uncle was still chained inside the underground jail in the royal castle, Alpheus felt obligated to return there and save his Uncle at least.
Maybe cleaned the vampires in the Eclipse Kingdom as well. The people might not appreciate him, but he was still the rightful Crown Prince of Eclipse Kingdom.
It was his duty to protect his people. It didn't matter whether they appreciated his help or not. It was still a duty nonetheless.
'But, there is no way I will go there alone. If I have to go to that world again, Sir Junshik Hyung must come with me, or else I will stay in this world forever! Everyone in that world can die for me to care!'
Alpheus tried to convince himself that he gave no shit to the people in his kingdom. But it was obvious that he couldn't stay still.
He still wanted to save his Uncle and his people.
