One popular 'Regulus Leaves with Sirius' fanfiction is 'The Departure's Echo'. It beautifully portrays their relationship and the emotional turmoil of Regulus leaving. Another good one might be 'Farewell in the Shadows' which delves deep into the reasons behind Regulus's decision and how Sirius reacts to it. You can often find these on major fanfiction platforms like Archive of Our Own.
Well, I'm not sure about a specific titled 'Regulus Leaves with Sirius' fanfiction off the top of my head. But if you search on platforms like Fanfiction.net, you might come across some great works. Usually, in such fanfics, the authors explore the complex bond between the two characters. They might depict Regulus leaving due to his loyalty to the Black family's dark secrets, while Sirius is on the opposite side, and this creates a lot of drama and heartache in the story.
There are quite a few fanfictions that could fall under this theme. Some fanfic writers like to focus on the magical world's politics and how it affects their relationship. For example, a story could show that Regulus leaves to protect Sirius from a certain danger that he has uncovered in the Death Eater ranks. This would lead to a very angsty and emotional journey for both characters, with Sirius feeling betrayed at first and then slowly realizing the true motives behind Regulus's actions. You can try using specific tags on fanfiction platforms to narrow down your search for such stories.
Chapter 278, ", The Phoenix's Icy Fury", is the clearest early answer because it turns Phoenix Monastery's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Irong Fatches knew that she couldn't possibly stay hidden in the... and follows through with The Allied Air Force's Wind Falcons swiftly descended upon the....
Chapter 383, ", No Choice", is the clearest early answer because it turns Martin Nelli's situation into a concrete plot event. The chapter gives readers a real answer by opening on For this very reason, Yan Fangxu couldn't help but use phrases like... and ending on In this scenario, Martin Nelli wouldn't necessarily die, but his....
Chapter 316, ", I'm Going to Die", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter gives readers a real answer by opening on The Rage Bear Legion goes without saying, they fight according to the... and ending on The reason for such ruthlessness is the result of Gu Hang's efforts..
Chapter 432, ", War is Burning Money", is the clearest early answer because the buildup finally cashes out in a real clash. It opens with And they were the true governors, the de facto emperors of their own... and closes on Whether I sign with the Alliance or not, won't they still have to.... The key payoff is that the danger stops being abstract and the conflict around Purple Horse Sector becomes immediate, forcing the surrounding cast to react under pressure.
Chapter 383, ", No Choice", is the clearest early answer because it turns Tianma Fleet's situation into a concrete plot event. The chapter gives readers a real answer by opening on However, despite knowing this, he couldn't easily promise those two... and ending on This strategy, overall, was based on the Tianma Fleet still stationed....
Chapter 419, "Turning the Tide of Battle", is the clearest early answer because the buildup finally cashes out in a real clash. It opens with Before the retreat, the human army wouldn't initially destroy the... and closes on Even with a fifty percent chance of winning, Gu Hang was still not.... The key payoff is that the danger stops being abstract and the conflict around Green Skin Fleet becomes immediate, forcing the surrounding cast to react under pressure.
Chapter 417, ", All Forces Attack!", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter turns that into something concrete by moving from Compared to the Seven Horse Treaty, the collection of Imperial Tax is... to The Green Skin Orcs of the Iron-Tooth Clan have been ravaging the.... What makes it stick is that the chapter closes with Tan Jiuyi let out a sigh.
Chapter 378, ", Star Language Phone", is the clearest early answer because it turns Gu Hang's situation into a concrete plot event. The chapter gives readers a real answer by opening on The so-called award ceremony was to commend Gu Hang for his... and ending on When the Rage Bear Legion was first established, it had only about a....
Chapter 331, ", The Great Battle", is the clearest early answer because the buildup finally cashes out in a real clash. The setup is Seriously speaking, being surrounded does not equate to victory., but the pressure keeps building through When the news that their rear was cut off reached the kingdom army....
Chapter 340, ", Fufana", is the clearest early answer because it turns Fufana's situation into a concrete plot event. A useful checkpoint is the way the scene starts with That exercise, it wasn't just her from the Fufana Family who... and follows through with Because that is you, that is the Yelisia I know and admire."....