Like back in the day, Wandering-Eye Anderson (seen by many as a predatory, opportunistic bisexual, but just has a misunderstood, perpetually-longing heart) lavished attention on the twitchy junkie that kept showing up at crime scenes, letting Sherlock use equipment and handle evidence when he shouldn’t, inviting him to the crime lab so he can see how NSY does things and maybe letting him poke around in databases/ run some tests. And Sherlock sees his own loneliness reflected in Phillip; as Sherlock starts to take a shine to him (because he treats him as more than a druggie and a fuck-up and a freak, he recognizes Sherlock’s brilliance) he thinks maybe Phillip would leave his wife after all. But then Sally transfers into Lestrade’s division and suddenly Anderson’s got a new fixation. Sherlock feels duped and brokenhearted; he tries to warn Sally and she tells him to fuck off, creating a decade-long antagonism between him and the two of them.
…That’s not how I was supposed to do the ask, probably, but I can see it like an angsty, artsy early-aughts rock video for a band with a sound like The Killers, except British. Crack ships are what fanfic is for.