Since Sebastian was kidnapped and forced to become a pet he has always been afraid of everyone in the house, that's what he thought at first until he found you

He saw you in the house he was confused at first like, why would a child be there with a bunch of insane freaks??? he thought but he soon discovered that Luther was the one taking care of you, but even so Sebastian didn't know how you got there (and didn't even want to know to be honest)

He was afraid of you at first (even though you were just a child) but as time went by he saw that you weren't so bad and he started to consider you as a little sibling even though he never admitted it

Now he was hiding from Randal (as always) inside a closet until he heard footsteps, light but a little careless, coming towards him, he thought it was Randal and that thought scared him more

his eyes widen when he sees the closet door being opened but to his surprise it was just you...it was a bit of a relief for him...