Complex sentence: Francis acted as the strongarm for Killebrew, reigning in the dying mercenaries that were fodder for Killebrew's sadistic experiments whenever they stepped out of line, mercenaries that included one Wade Wilson, who would later take on the codename of Deadpool.
Split into simpler sentences: Francis acted as the strongarm for Killebrew, reigning in the dying mercenaries that were fodder for Killebrew's sadistic experiments whenever they stepped out of line. This included one Wade Wilson, who would later take on the codename of Deadpool.