"All lives end. All hearts are broken. Caring is not an advantage."
~Mycroft Holmes, A Scandal in Belgravia
Caring is a disadvantage. Mycroft Holmes cannot remember when he learned this; it seems as if he has always known it. There is very much to lose and nothing at all to gain by letting another human being into your heart.
Caring means you get up at three am when begged to triple-check for monsters under the bed, and share the last piece of cake to keep the tears in those precious blue eyes from spilling over. It means drying those tears when the world's most tattered teddy bear falls in a mud puddle. It means sacrificing precious study time to sword-fight with empty paper towel rolls while wearing construction-paper eye patches. It means sharing your bed because there's a scary thunderstorm, and letting your fingers grow numb rather than move and wake him when he falls asleep on your arm.
Caring means taking the long way to class to drop him off at primary school, and getting laughed at by your mates for it later. It means letting him borrow your telescope, and not getting (too) angry when he breaks it. You bear his criticisms and insults to your intelligence, knowing he doesn't mean them personally. You stand up to bullies for him. It means you pick him up from the headmaster's office and sign the note he's supposed to bring home about his classroom behavior, because you care too much to let him face Mother and Father.
Caring means you pull whatever strings you have to to get him into the university he wants. You continue to stand up to bullies for him, when he lets you. It means you notice, even before your mother does, when he begins to lose weight rapidly and seem tired all the time. It means confronting him and even taking a punch because you pointed out the telltale marks on the inside of his elbow. It means that six months later you pick him up from the police station so he won't have to tell Mother, but also that you track down all his dealers and threaten them if they sell to him anymore.
Caring means that you continue to watch and worry even when he has long since turned his back on you. It means tracking down that man – that ordinary man with the extrodinary heart that has somehow snuck into his closed-off world – to see if he will help you watch and worry. When he will not, you are still comforted that there is someone in his life who will look out for him. It means that you take pains to see that that extrodinary man does not act rashly out of grief when his best friend seemingly deserts him. It means even allowing yourself to feel the human weakness of regret when you see how your betrayal has aided Moriarty. Of course, you have deduced for yourself that the events of the rooftop were not what they appeared to be.
These little sacrifices can be borne, these are not the real disadvantage that comes with caring. Caring even when you can't help it, even when all you want is to turn yourself to stone and not care. The Ice-Man, they called you, and the Ice-Man you want to be. But you know you care because when he sneers, when he turns you out of his flat and shuts you out of his life, when he blocks your phone number and ignores your birthday and talks about you like you're nothing at all to him…It hurts. every. time.