I know it's unconventional, but I thought it through a whole lot.
I filled out a profile sheet for him, that may help explaining, along with a dex entry sorta...thing.
Moves- Night Slash, Dark Pulse, Shadow Ball, Haze
Characteristics- Often Lost in Thought
National Dex No./Species-
#650 Insombreon/ The Plague Owl Pokemon
Pokédex Entry- This Pokemon never sleeps. It stalks its' prey mercilessly until it catches it.
Item- Smoke Ball
As Plague traveled throughout NewJohto, he faced many horrors and fought through impossible odds. He sought only to be reunited with his trainer, Toluca Bering. One terrible night, he had finally found her...torn to pieces under his own claws. Unbeknownst to him, the virus had begun to mold itself around his genes, manipulating itself so it would gain a firm hold on his mind while he slept. He had found her, only to lose her by his own doing. He was torn apart by guilt and rage.
He had found a small place to bury her belongings, someplace important to the both of them. As he emptied her satchel, a dusk stone fell next to his paw, and he began to glow. The Honchkrow skull on his face combined with his own DNA, melding the two together.
He was now an Insombreon.
- Insombreons never sleep. They usually stalk their prey in the day and hunt at night, when most creatures are sleeping, so he can ambush them when they are at their weakest.
- His rings and eyes only glow when he is in attack mode.
- His eyes are empty black sockets when not glowing.
- He evolved due to extreme darkness in his heart, combined with the aura emanating from the dusk stone.
- Plague has grown cold and heartless. Responsible for the death of his only friend, he uses that as a reminder to never get close to anyone ever again.
- He has succumbed to the darker aspects of himself, including the what the virus is doing to him. He has become very bloodthirsty, unforgiving, ferocious.
- He has retained his intelligence and memories due to his special genetic makeup of an Eeveelution. He won't rot and he isn't undead. He is just severely mentally damaged.