[This, only change one letter to fit the context.]
[And yes, well... usually Sebastian's reassurance is followed up by killing whatever lowlifes caused the distress, so this is in every aspect new territory. Might as well try a slightly different enabling reassurance tactic.]
And were it not for you, were it not for our bond, I would not be the person I currently am, [he continues, not taking his eyes off Ciel.]
This name, this appearance... all I say or do whilst in your service is tied to you, and you alone. I would speak not to a single person here, were it not for you, would I?