A simple change to Varus to keep everyone happy
Scrap the two lovers bit. Replace Kai with Varus(Valmar?)'s son. There you go. Old fans are pleased Varus is still Varus, and he can still perfectly fit into new lore - hell, you wouldn't even need to redraw the comic for the most part. -Make Varus' son a hunter in training, so the beginning of the comic still makes sense. -Varus giving himself to the corruption to save his son has the same, if not more weight than doing so for his lover. -In the end Varus' lore can still be expanded in the same way - really, just replace "lover" with "son" as the voice helping his father to stave off the Darkin and as a reason for him to resist and live until they can possibly cleanse themselves. New motive of love being able to fight the Darkin is still there - it's just fatherly love instead of a romantic one. Old concept of a man who can't take the loss of his family and surrenders to the corruption is still here. Everyone profits.
You can write him in his new lore. You can combine it with the old one. However you go, I assure you this will satisfy the vast majority of complainers - except SJWs whining that their toke gay character didn't make the final cut. But you know what, Riot? Man up and tell them where they can stick their whining. This is YOUR IP, and you can do whatever the hell you please with it, no matter how many internet white knights you trigger. Your old fans should be in the first place anyway.
And yes, I know I'm beating a dead horse. But these boards exist so that our opinions can be heard, and the louder we are the more chance we get through story team's ears and into their thick skulls.