#!/usr/bin/env perl

use strict;
use warnings;

my $txt = "
Title 1
Line of text A
Line of text B
Title 2
Line of text C
Title 3
Title 4
Line of text D
";

my @reverse;
my @normal = split /(Title \d)/, $txt; 
foreach my $n (0 .. @normal){
  if ($n%2){
    push @reverse, $normal[$n].$normal[$n+1];
  }
}
chomp @reverse;
@reverse = reverse @reverse;

map { print $_."\n" } @reverse;