Originally Posted by chparadise
It could be as simple as he was presented much the same choice as Dean's father - "join us or die". Negotiations at wand-point can produce results. Voldemort may have known he was the weakest of the marauders, and he wanted an "in" to the stronger ones, who'd rebuffed him. Peter was a good opportunity here.
You may be correct and if that were the case, Peter had many, opportunities to tell Dumbledore or his friends that he was coerced by Voldemort and he had at that time, no other alternative , but to take the mark. He could have become a spy. He could have been protected in other ways by Dumbledore.
He was able to stay as a rat for 13 years; that shows us he was capable of survival by any means. Even if he had to live like a rat.
He never told anyone, if he was forced to become a DE, I mean, and he spent his days until he had to change into a rat, by happily passing information that led to so many deaths, including that of his friends.