Dark Mega Talia! Still not her final design though so its not really good, I’m still thinking of alternatives :C

STORYTIME 8D

Talia used to have a very abusive trainer as a Kirlia, so as she grew up into a Gardevoir, her understanding of affection became perverse and twisted and she eventually kills her trainer with her “love”.

She absorbs the mega key she took off his corpse and can only evolve into a corrupted version of her mevo.