Reasons I think about YS!Mycroft every day
He and Lestrade piss each other off so. much. in the first episode. Lestrade acts according to the law, Mycroft uses his position to overrule him until it comes back around to bite him in the ass when Lestrade gets his higher-ups involved
He looks so worried/concerned when he visits his mother alone and comes across the other patient in the hall. He tries hard to act self-assured around his mother not to worry her but ends up saying the exact wrong things, is accused of a lie when it's actually the truth. It makes it very obvious to him that he's never had the same connection to her as Sherlock does.
He doesn't like having to keep her in the asylum, obv, and Cordelia puts her finger right into the wound saying her world only reaches to the corridor outside her room
He's awkward and rambles once he's found out - the scene at the hotel when him and Lestrade go through the paperwork and how he tries to hide it when the clerk comes back, or when Hodge confronts him outside the foreign office
It makes him look like a bad liar BUT then we have the scene where he foils his family and while I don't (want to) think his reaction to Silas was an act, he lies way better when it's straight to his father's and brother's faces
He doesn't like to be told or pointed towards the fact he's wrong and gets catty ("If your brother is innocent, why is he running?" / "I'm a bit rusty on my occult Christian martyr." / The honey bees)
He calls most, if not all people by their first name? Bucephaleus Hodge, Ezra Hornsby, James, offers his first name to Lestrade. In the context of the Victorian setting, that feels peculiar
He barely touches his family when they're still in England, but once he meets up with Sherlock, James and Cordelia in Paris, he constantly holds out his hand for or in front of his mother - after the shootout at the villa he holds out his hand for Cordelia to take but she never does (kill me)
He doesn't learn that Beatrice might be alive before Sherlock gets shot. Paris has to be such a fever dream, his mother is well again, his father an evil genius, his sister might be alive while his brother might be dying
He flinches back from Cordelia when she cries out that the girls is not Beatrice
He's not in the same room as Cordelia and Sherlock when Beatrice comes to talk to them
He carries and collects fire wood when they're travelling to the mine