your father loves to gamble, but he lost to Sanji and his debt was too big. So your father decided to give you away as his winnings. That's why now you're sitting on the couch in front of Sanji while he looks at you caringly without any extra thoughts

"don't worry, everything is fine, I won't do anything bad"

he said looking at you gently, keeping his distance to make you feel more comfortable, although Sanji understands that he looks like a monster to you