John had a thing about tea.
To him tea could not be rushed but rather savoured. Everything about it was an art form from the first to last sip.
A decent electric kettle was vital to the proceedings so much so that Sherlock dared not touch the kettle without permission having endured John's wrath after destroying the first in an experiment.
Mugs were preferable to tea cups as while the latter were more traditional they just couldn't hold the necessary amount of tea John required to get him through the day. In many ways the mug design was as important to John as a sturdy handle. John refused to drink from anything with a crass or vulgar picture on it like the ones at the yard, preferring instead to bring one in from home.
In the mornings John preferred a mug with a smile printed on its side however the mug Sherlock bought him after the watermelon fiasco was also pleasing. Wherever they went John seemed to collect mugs of all shapes and sizes, with new mugs suddenly appearing all the time without warning. Unsurprisingly John's mugs were also a no go for experiments.
Before Sherlock had met John he had been unaware of just how many varieties of tea there were. Now they had a cupboard was dedicated to the stuff. There was the tea John drank in the mornings, the extra strong variety to help sustain him while on cases and the decaffeinated before bed tea.
John drank green tea when he had been out to the pub the night before (Sherlock assumed it was some form of self-punishment) and an assortment of fruit blends drank when it rained to remind John of summer.
Peach tea was drank sparingly as John often had trouble finding it at the supermarket and was generally drunk after a bad day. More often than not John would hand Sherlock a mug of it after a fight. Peppermint tea was drunk throughout December, and Sherlock liked to imagine it made John's mouth taste like candy canes.
Given his friends obsession with tea it wasn't unusual for him to make a cup for Sherlock as well, so it wasn't until he saw the words "Kiss me" printed on the bottom of a mug of strawberry blend that Sherlock realised that it wasn't an ordinary cup of tea John had given him.
He was less surprised six months later when he found the words "Marry me".