How about using our.

#!/usr/bin/perl
use strict;
our $pie;
require "b.pl";

&getpied;

print "The pie says : $pie\n";
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The pie requires script b.pl

#!/usr/bin/perl
use strict;

sub getpied
{
    our $pie = "eat me";
}
1;
[download]

This outputs "The pie says : eat me".

Also, about using strict, it must be done in every script.