The man with blue eye's

Mark doesn't care who the person is. He'll take what he can get and kill them. Never giving mercy.

On the other hand, Sean has never murdered an innocent pedestrian. Instead of taking their lives, he takes their valuables instead.

Both love to steal.

Both dislike one another. Well that's not particularly true. Mark has a cold heart. Not only Sean is warming that heart of steel but he's also 'stealing' it too.