I have a close friend who speaks of stalkers. He's the smartest man I've ever met. Seems pretty damned connected too, when you speak with him. Actually, you can't tell he's paranoid until he decides to share his torment with you. He's told me about people walking around in passages through his walls, rearranging things in his home, jumping up and down on his roof, using advanced devices to remotely manipulate objects, and projecting thoughts and moods into his head.
My buddy supported all these wild stories with some pictures of a couple guys standing on the street by his mailbox and some stills he had stitched together into an animated gif theoretically showing people jumping up and down on his roof. His evidence was crap. From what he tells me about the guys at his mailbox, he's met them out in public, acted like a complete freak to them, and now, surprisingly enough, they treat him like one. As for the pictures of the people on the roof, there's nobody there. Just trees blowing in the wind. The jewel in his crown of proof was the fact that all these things happen to other people too.
http://www.raven1.net/glossary.htm
So, yeah. That website demonstrates that there are whole groups of paranoids out there who truly believe they are being persecuted by some huge organization. That really doesn't equate as proof of the stalkers. My buddy knows all about scientific method and proof, and would never present this kind of evidence about any rational subject.
Two final points of interest about my friend's view from over the edge:
1. Prior to being targeted by 'them', he had a strong desire to die. Being forced to defend himself has given him a perverse reason for living.
2. He's dangerous in his pursuit of that desire. He's set up surveillance and deadly traps, covered his roof in Teflon (so the roof jumpers would slip off), and engaged in week long vigils to catch them in the act.
Don't feel bad about messing with Perseus. If he's close to as far gone as my buddy, any sort of social interaction where he gets to discuss his stalkers with non-paranoids is a positive thing. They aren't getting the message that the stalkers don't exist, but it remains our responsibility to gently point the way to a more mainstream mode of thought.