Normal eyes Plague is for in-school and such. He's less aggressive towards others.
Glowing eyes Plague is Dark World counterpart. He's a lot more aggressive to those he doesn't know well or whoever threatens him. Use lavender against him; it pacifies him.
When he get's really angry... you better run. It's PLAGUE TIME for him. He will try to hunt you down for a while. As long as you outrun him you should be good for a while. But still, it's better to carry Lavender.
HEY CHAT. I ADDED MY SPRITES FOR THE DARKWORLD IN DEMI'S HIDEOUT. ALL MY SPRITES ARE WITH MASK. REASON WHY I CAN'T POST THEM ALL IS BECAUSE THE PROCESS IS TOO DARNED LONG! BUT IT'S PLAGUE DOCTOR.
(SOMEONE SAID IT LOOKS LIKE ITS FROM FAMILY GUY)