Yay for Eldest Brother Mycroft! Also, everyone's reaction to illness in the house is perfectly in character from Sherlock's mentality to wage war against it to Mr. Holmes being so relieved to avoid the entire house but still caring.

Out of all the wonderful parts in this, I think my favorite segment is Mr. Holmes giving his son the ciphers. I love Sherlock quickly asserting he knew the quote too after Mycroft beat him to it and Trevelyan initially struggling a bit before getting his. It's so wonderfully realistic.

I also enjoyed Sherlock's insistence that the romance bits of The Scarlet Pimpernel were boring. Oh, Sherlock. You just never changed.