[Putting "Lucifer" and "thinking" in the same sentence is already ridiculous. /badum-dish]
[Sebastian knows Lucifer well enough by now - and recognises the odd look as thoughtfulness, or whatever the Lucifer equivalent of that would be - not to take the comment as a jab; no "you managed to save him despite having such a difficult time of it and looking really pathetic".]
Sir, I realise that the attention you pay children is lacking at best, but that child is my master. [No duh he saved him. It's. only his job.]