Sylver Cielo knew this would happen sooner or later.
Reynold Alasdair admitted that it was not Ruby Alasdair who told this to him and Richard Alasdair. They said Theodore Cielo himself accidentally called him 'Father' instead of 'Brother' when that day he jumped into the river to save Ruby Alasdair. Reynold was even as confused as he was when he said that Ruby knew this because Ruby came to the Bliss empire and accidentally saw his wedding to the late Duchess.
This, of course, was denied by Reynold because on Sylver Cielo's wedding day, Ruby Alasdair never set foot outside Alasdair's mansion.
"A son?" Duke Alasdair frowned and looked at Sylver and his eldest son in turn. "What does this mean, Duke Sylver, Reynold?"
"Theodore Cielo is not my little brother," Sylver answered in a calm and firm tone. As calm and firm as his purple eyes when looking at Duke Alasdair. "He is my son. My biological son."
Duke Alasdair blinked and his mouth opened wide.