Lyric discussion by his_teddy 

Cover art for Metro lyrics by Vincent Black Shadow, The

I agree more with lithiumprincess that it has to do with a mental illness.

Blinking, thinking something’s moving across my skin I think she suffers from paranoia. When a person is paranoid, they have tendencies of having delusions.

"“Swallow this” and for once I’m mistaken" She may be in a mental asylum and the nurses make her take medication, to relax her.

I think when it says:

"Now he’s back again And now he’s brought a friend. And his friend’s brought a whole dark army…"

She may have been going crazy. So the doctor came back, with a bunch of nurses, to sedate her.

I don't know, just a thought. Awesome song though.