Answer:
I am a protector. I sit on a bridge. One person can see right through me, while others wonder what I hide. What am I?
I am in the past, never in the future. I don't exist, but have existed. I saw what you saw, and this is what I will ever see. What am I?
The time between daylight and darkness when blood drinkers like to come out
If you lose one of me, you are upset, bewildered, and perplexed. If you lose two of me, you are blissfully unaware. What am I?
Only one color, but not one size. Stuck at the bottom, yet easily flies. Present in sun, but not in rain; doing no harm, and feeling no pain. What am I?
I fly to any foreign parts assisted by my spreading wings. My body holds an hundred hearts Nay I will tell you stranger things when I am not in haste I ride and then I mend my pace anon.