After Professor Zoom, in his Reverse-Flash identity, journeyed with his cronies on the Secret Society of Super-Villains to various parallel planets in the Multiverse... including Earth-Two... he returned to his native Earth-One to once more grab the attention of Iris. However, she continued to spurn his advances, leading to his attempt on her life at a masquerade party she attending with her husband Barry "the Flash" Allen. Despite this seemingly being her untimely end, in fact due to her originating from the 30th century her parents of that era used advanced science to emulate her mental impressions, inplanting them in a cloned body that would one day be reunited with her true love. However, before this was to happen, Flash would have to face off versus Zoom both immediately after Iris' apparent demise (when his own time travel device ended up sending the Flash to a limbo where he would meet its evil Lord, who would himself complicate the lives of Earth-Two's Flash and his wife later) and then several months later when Zoom attempted to replicate his nefarious feat upon Allen's fiancee Fiona Webb. On that occasion, it was Zoom who perished when his arch-foe out of self-defense protected Fiona at the cost of the Professor's existence. After leaving Fiona on the alter, quite literally, the Flash came to realize that he had to face justice for the slaying of his opposite opponent, even though it was unintentional. And, in fact, it was Iris herself who with the aid of an unsuspecting attorney successfully defended the Scarlet Speedster from the spurious charges lodged against him. Once the couple left the 20th century for Iris' time, they were able to settle down... albeit only briefly before the Flash gave his life during the Crisis on Infinite Earths for all Earths! But not before they would concieve twin children, Don and Dawn, who would carry on the Flash's tradition.
And yet, inbetween the time Barry-Flash thought he lost his love and when he learned she was awaiting him elsewhen, he had to intervene in his counterpart's life, as Jay-Flash faced an equally dire threat facing his wife, Joan! For this, we come full circle in our final Flash of Two Worlds teamup, when once more an old ally of the Scarlet Speedsters was needed to save a wife of a Flash!