When Rosie is ten, they move to Sussex. It’s only a semi-retirement Sherlock will commute into London if the case is a 7 or higher, everything else he can pretty much do from the comfort of his own home.
Rosie is brilliant as she grows and when she’s fourteen, she announces she’s going to be a Forensic Psychologist, despite several conversations she doesn’t budge. It’s no surprise when she has her pick of universities in London even without Uncle Mycroft’s meddling. Everyone is misty-eyed when she moves to London.
Sherlock worries immensely because he remembers his on uni days. After intense negotiations, John agrees it’s ‘reasonable’ to text her 3 times a day unprompted. The rule doesn’t matter because she texts them constantly, telling them about her day and asking about the things at home.
Rosie being Rosie immediately involves herself in a ton of extracurricular stuff. One of her groups volunteers regularly at soup kitchens. The first couple of times she’s volunteering there are a few people who stare a bit too hard at her. Finally, she snaps and asks one of the older women who have been staring for the past month what the hell their problem is. The woman laughs and only says “No different than your father then.”
Rosie ends up involved in the homeless network, except she’s even more approachable than Sherlock because she’s 5′3″ and inherited John’s friendly face and some of his jumpers (she know they’re hideous but she wears them when she needs a boost of courage. It’s not uncommon for her to wander around in a hideous jumper and a cashmere scarf during exams.)
Rosie’s heart shatters when a batch of tainted drugs gets sold and several of the people she’s grown to call friends, die. Sherlock comes up and discovers the source, it turns out to be a case full of murder and intrigue but even if it hadn’t been he could never stand her tears and would have come anyway.
Neither John nor Sherlock are really surprised when Rosie calls home one day and announces that after she finishes her Psychology degree she’s going to take a post-grad course in addiction studies.
Even though when she graduates it’s John who spends days gushing over how brilliant she is, it’s Sherlock’s quietly spoken “your heart would have been wasted on criminals” that lets her know she made the right decision.