Until this moment, despite knowing that there was a great possibility that someone from the Santos family was involved with the death of his parents, Michael had no intention of changing his surname.
This was the name that he had been given by his father, hence, Michael had no any intention changing it.
Still, if there was going to be a big conflict with the Santos family, then he might just as well destroy the existing Santos family, and create another one.
That would be able to solve quite a number of problems.
On the other hand, upon receiving Michael's confirmation, Marion was both excited and shocked. She had already anticipated such a possibility, but she found it too unbelievable.
After all, what was the possibility of something like this happening? When she was in danger, she just had to encounter the son of her long lost aunt, who ended up saving her.
