Sometimes he wishes his parents had just stayed put and he could have gone to Durmstrang. At Durmstrang, as he understands it, a primary skillset of talking, fighting, and knowing things about nature gets you a fair distance. At Hogwarts, you mostly have to write a lot of essays, a skill that he absolutely does not have and has never been able to acquire despite continuous and deeply frustrating effort.
Sometimes his mother owls him to tell him, pointedly, that yet another of his distant cousins has apparently died horribly, though, so, you know. Upsides and downsides.
He gets a handful of barely-passed OWLs, tries NEWT classes for about three weeks, and then pays one of the 7th-year Slytherins to teach him to Apparate and disappears to Norway. No one except his mother is surprised.
Everyone is surprised when he turns up again three years later, and nearly gets hexed by half the Order of the Phoenix when he casually shows up for one of their extremely secret meetings to cheerfully inform them that he has spent the last year collecting a list of the holes in their information security (to whit: have they considered setting up some sort of coded messaging protocol instead of having their secret conversations in public alleyways just because they think they're alone and have never considered the possibility of someone using normal stealth instead of being magically invisible, oh my god, why are Gryffindors like this?). The war still goes pretty badly, but still only up to the part where Lily Evans pulls some sort of insane bullshit out of her hat and/or her ovaries (whomst the fuck knows, certainly not ancillary Hufflepuffs).
Sasha subsequently spends a very peaceful ten years fixing clocks in a dusty corner of Diagon Alley before Harry Potter gets killed by a basilisk in 1992 and all hell breaks loose again.