Problems with Varus' old lore.

First and foremost, his old lore was completely and shockingly unoriginal. Comparing it to other league champ lore, or external lore from other games/series/etc. A person goes through a tragedy, then goes to extreme lengths to do whatever means possible for vengeance. I've heard it a million times, I said it the first time I read his lore and I still think that today. As for his family, an extremely large portion of the characters lost their family one way or another.

His old lore had nothing to do with becoming a Darkin, and that over all is what Riot is intending with this new lore. Turning Varus into a Darkin with a background that make (kind of) sense. Sure, you could have said that the old pool he fell into consumed him and turned him into Varus. Or he picked up the cursed bow in an attempt to gain power. But that all brings it back to my first point, it's been done before.

Love, on the other hand, is something that's seldom been a factor in prominent league lore. Yes, there's always been a hint there, or a crush there. But when has love, an unbreakable bond between two people, been the key to a characters background (Excluding Xayah and Rakan, my two favorite characters atm).

In the new lore, Kai and Valmar had such an unbreakable bond. The decision to go into the pool was in the heat of battle, and they had no idea what it was going to unleash. Old Varus literally got pissy about his family dying, and jumped into a pit of corruption. Intentionally.

As for those who just don't like them changing an entire character story, Riot already said any old lore is no longer canon. Varus' old lore meant nothing anyway, just be glad it got picked up by such a great story instead of ruining it.