- Thea's death.
- Made worse many issues later. While fighting The Shadow in its own realm, Rat-Man managed to reach a world in which Thea was still alive... And discovered the only world where she could be alive was one in which they had never met and fallen in love. Just as planned by the Shadow, as the hope of meeting her again was the one thing enabling his status as a Determinator.
- And then, some issues later, the whole truth about Thea: she was actually a clone of Aima, professor Denam's real daughter. Aima, and not Thea, was the one Rat-Man fell in love for, and they successfully escaped Denam's lab, but Denam and Topin, under Kalissa's orders (who was planning to use the whole thing and Aima as a weapon against the Shadow), had Rat-Man's beaten and his memory wiped so Thea, who believes herself Aima, would die in Rat-Man's arms, while Aima had her own memory wiped and lived without remembering her own father knowing she had fallen in love until a month later, when the story of her clone was published in-universe and she realized it was about her and checked it with Krik-but seeing Rat-Man's picture didn't tell her anything. Then there's the other Thea, Rat-Man and Aima's daughter, who Aima and Krik kept in the dark about her father to protect her from the Shadow, but many years later Aima told her the truth, and while she managed to meet her father he was already possessed by the Shadow. All the hints we had about this was the Incredible Ik (an incredibly strong guy who looks like an unmasked Rat-Man with yellow skin and is the personification of his love for Aima) breaking out of his cryo cell and rampaging through the City With No Name while searching for Aima and a woman looking like Thea appearing before her cloning chamber and suggesting her name.
- And then, when Rat-Man discovers Aima is still alive and they have a daughter, he runs to Aima... Who tells him she can't remember him.
- Rat-Man's relationship with Kimmy, the only other woman who came close to be for him what Thea was. When they were children they were in love, and Rat-Man, then Rat-Boy, knowing she wanted a boy who, in her own words, went around with a bicycle and not Roof Hopping, was ready to throw away the mask... And when he arrived he found a bicycle and left, knowing she had grown annoyed enough with him to dump him. Except Kimmy was still waiting for him to run away with him, and the bike was of Ortolani's friend Vassilli.
- Years later they meet again, and, having found out she's both the Spectre and the Wolf's daughter, knows why she's so adverse to superheroes. A chance to reconnect? Nope, she's now married with a cyclist named Joseph. And the bike he broke in revenge wasn't even Joseph's... At least he finally got his revenge on Vassilli.
- In the Vendicatopi-Mr. Mouse story arc we find out Kimmy and Joseph broke up, as he wanted children and the experiments that gave her superpowers also made barren. This time they reconnect, after the final battle there's a chance Rat-Man and her will finally get together... And then Kimmy finds out she's pregnant and Joseph returns to her.
- Ricordati di me ("Remember me") has the final confrontation between the "memories" of Janus and Joba Walker. "Joba", after his plans have been foiled and all his mooks have been killed, tries to make "Janus" pass on his side, telling him that he's fighting for scraps of paper (the memories that "Janus" has been trying to collect through the two issues, as a mean to make Rat-Man remember him), and how it's "unfair" that he's trying to sacrifice everything when the real Rat-Man won't even know that a memory of his father still exists. "Janus" concedes that yes, sacrificing yourself for the sake of someone who won't even remember your existance is unfair... but that's what fathers do.
- When he was a young scientist (and assassin), Valker rescued Deboroh, the future Rat-Man, because he had discovered he was his son, and tried to be the best father he could, even forcing the labs to put him in the Second Secret Squad in Nottolo's place. And then, Joba tells him that Deboroh is not his son, he set up everything-and gave him the address of Deboroh's real parents. His reaction to Joba's words, and then when he sees it's true-and just how bad Deboroh's real parents are, is heartbreaking.
- Valker's final act as a father: knowing he's about to be possessed by the Shadow, he wipes Deboroh's memories of him and his own memories of his son and sends him away for protection. Made worse because this is when Deboroh tried to leave with Kimmy and thought she had left him.
- Speaking about Valker's last act as a father, the very last moments he spent with Deboroh might be the saddest moment in the entire Origins storyline: Valker shortly loses his albinism, just in time to make his son run away from the Shadow. Just the contrast between his resigned sadness, when up until that point he was desperately trying to escape his destiny, Deboroh's attempts to make him escape with him showing how much he loved him, making Valker call him "the best son I've ever had" and the fact that Valker would become Rat-Man's arch-enemy and Deboroh would lose the memory of the only person who loved him is just heartbreaking.
- The whole story is told by Deboroh to the guy he shares a train compartment with, ending with a desperate request to repeat him the story because the mind wipe is about to take effect and replace his memories, and he doesn't want to forget his father. Except the travel mate is Leo Ortolani, who doesn't tell him because he wants to continue the series.
Tear Jerker / Rat-Man