Did we mention that this fic could also be titled ''A Study in Family''? No? Well, it deserves to be mentioned!
* InspectorLestrade, from his very first appearance, really takes up the role of being a ParentalSubstitute to SherlockHolmes. The good Inspector could also be said to have a BigBrotherInstinct, but it's really more like he's adopted his amateur colleague. As Holmes heals, he's coming to terms with a lot of things, essentially becoming a new person - he very much needs a father-figure in his life.
** Much of their dynamics is made up of Lestrade being a DeadpanSnarker while Holmes ''tries'' to keep up (he kind of lost his conversational supremacy at Reichenbach). It tends to be a glorious mixture of humor and fluff (see the [[Funny/AStudyInRegret Funny entry]]).
** Except for when Lestrade gives him a WhatTheHellHero talk. Then it descends into TearJerker territory.
* Speaking of parental substitutes, Mary really plays the trope brilliantly as a surrogate big sister/mom to both Marcel and Holmes (amusing [[FridgeLogic when you think about it]]: Holmes has at least a couple of years on Mary). Plus, she quickly establishes a [[LikeBrotherAndSister sibling-esque relationship]] with Lestrade.
** Most of her scenes with Holmes are Heartwarming Incarnate, especially the twin scenes of embraces and tears (see the [[TearJerker/AStudyInRegret Tear Jerker entry]]).
* The BirthDeathJuxtaposition. ''Dashed'' if it isn't heartbreaking when you think about poor Watson, but the fact remains that ''Mary is having a baby''.
* Once Holmes and Marcel get their issues out in the open, their interactions are really very sweet to read. And doggone if, when they go into town, Marcel doesn't sound like a kid ready to get in trouble with his brother!
* This. Just ''this'':
-->After continuous days and nights spent in each other's company – working, talking, arguing and just generally learning how to live under the same roof – the four of them have become a mostly functional... team? No, Holmes supposes that 'family' really is the only term for it. It can never take the place of what he and Watson had... but he has been relieved beyond measure to find that the other three have instinctively understood that, without the need for words. What they have here doesn't feel like a replacement, as such – merely... an extra, something that could even have been present back home, had he had the mind to acknowledge it...