Conclusion

"I, Letizia La Scola, shall be the slave of Alexander Sirius for the rest of my life as I swore my eternal loyalty to him, and all the things I have is his, including my treasure, my body, and my life." 

The Oath had been established. Although it was similar to Heavenly Oath, the word 'Eternal Loyalty' had a big meaning. It was more like a Slave Oath, rather than a Heavenly Oath.

Alex also felt something because of this oath. He felt that her life is linked to him.

If he wanted her to die, he would just need to think about it, and her life would be over. Alex then narrowed his eyes, asking himself, 'Is this girl a fool or something? I have yet to promise that I will not do something to them. I can still kill all of them and have her as my slave. Fu… This girl is lucky enough to unconsciously win a gamble since I am not someone who will break a promise.'

"Letizia, you!" Cecilia was grieving about the fact Letizia became someone's slave.