The High Elves that are IN the Alliance never left after the Second War. That's why they survived the fall of Quel'Thalas they've been separated for years.
Actually many High elves that joined the Alliance were part of the elves that left after the Second war. They left Quel'thalas because they apposed Kael'thas' teachings. Maybe you should brush up on your lore.
Only in the decannoned RPGs.
Which you seem to keep claiming as fact.
Should we start quoting the ones that say Blood Elves are changing into another race then?
Actually no, I'm not even referring to the RPGs, these are official lore, even posted in the Wowpedia. You seem under the impression that the only Alliance High elves were the ones that remained after the second war, when that number is actually very small compared to the exodus of High elves that left when they apposed siphoning magic, and fel.
"Following the high elves' banishment from Quel'Thalas, some of them chose to rejoin the Alliance, and the night elves were among their greatest critics. While the traditional allies of the Alliance treated the high elves to a cold reception and suspicion due to their secession after the Second War, the night elves took it upon themselves to warn the Alliance (which they, too, were now a part of) against the high elves"
https://wow.gamepedia.com/High_elf#High_elven_relations
"A particularly lingering grudge lies between the kaldorei and their Thalassian descendants: night elves generally view the high elves and blood elves with disgust, suspicion, or outright hostility."
https://wow.gamepedia.com/Night_elf
Gnomes
"They are wary of the high elves, but so is everyone else, so they don’t feel too bad about that."
https://wow.gamepedia.com/Gnome
But I guess you aren't gonna acknowledge this either?
There are High Elves hanging out with Void Elvs in Stormwind and studying the Void in the Rift.
There's no reason to think that they don't know about the Light and Void reactions.
Studying the void =/= wanting to be corrupted by the void
There's no reason to believe they would have any idea of the void interactions, as Alleria herself was unaware that her presence would corrupt the Well. There is nothing that suggests that they are aware of the effect they have on the Sunwell, to assume otherwise is conjecture. The burden of proof lies with you to prove otherwise.
Talk about headcanon. The Void Elves aren't a disease and if they Void Elves where to threaten them they would hold up in their homes in Alliance lands just away from the Void Elves.
Why would they go to a place in the Horde with people the did not want to join after the Second War and leave their family and friends?
Alleria infected, and almost corrupted the Sunwell. The Void does corrupt, that's it's whole purpose. It whispers in their ears, and attempts to influence them to preform heinous acts. I never said that the Void elves would threaten or attack the High elves, merely that it is possible that their presence could effect nearby High elves, but as I already clarified this is just a theory as the extent of the void's corruption is unclear. The point was it's a very real possibility that Blizz could go down. Perhaps you should read.
Their families and loved ones are in the Alliance. Not Silvermoon.
Dalaran High Elves have been living there for 3,000 years. When told to leave after the Second War they stayed.
Quel'lithien was attacked by Horde regularly and when asked to rejoin by Lothamar they threatened to decapitate him. The few that survived still hate the Horde.
Quel'Danil have been and still are Kill targets by the Horde. There are Blood Elves that are part of the group attacking them. They have completely forsook Arcane magic and are close Allies with the Wildhammer Dwarves.
Allerian Stronghold have been living on Outland for 30ish years with Humans and Dwarves and detest the ways of the Blood Elves.
Then all that's left are the scattered bits that make up the 7th Legion, currently at War with the Horde, and the ones in Stormwind who have been shown to be close allies and friends as citizens there.
There's literally no High Elf group that would join the Horde. They would have done so already or have been assaulted by the Horde at some point.
The high elves that were banished from Quel'thalas have been gone for barely a decade... They most certainly do have Family and friends in Silvermoon. Didn't I already give you an example of this? There are dozens of High elves that share last names with Blood elves, and even a questline revolving the High Elven wife Vyrin Swiftwind, and her blood elf husband Talithar Swiftwind. You either are ignoring massive parts of in-game lore, or you simply don't do any research.
And the Horde regularly attacks the Quel'lithien lodge? There was only one attack on the lodge, and that was from Nathanos to retrieve the Farstrider registry. Are you literally just making things up at this point? And this is largely a moot point anyway because all the High elves at that lodge either died or became wretched.
The only reason the Quel'danil lodge are "kill" targets is because they are officially alliance members. There are no Blood elven quests to attack them, and Auric's relative Gilveradin Sunchaser is a friendly unit to the Horde, just beside the Quel'danil lodge, where he states he has no interest in the faction wars, and is even friends with some Orcs in Orgimmar. I doubt he'd like the Horde if they were trying to kill him.
Yet Auric Sunchaser, the leader of the Allerian Stronghold is one of the largest advocates among the High elves preaching the unification of Blood and High elves. There has been no evidence of any of the elves saying they detest blood elves, is this just more of your own headcanon?