One popular 'highschool dxd gremory fanfiction' is 'The Gremory Heir'. It focuses on a new character who is related to the Gremory family and their adventures in the high school dxd universe. Another one could be 'Gremory's New Power' which explores the discovery of a new and unique power within the Gremory clan.
Well, there's a fanfiction called 'Gremory's Alliance'. In this story, the Gremory group forms an unexpected alliance with a group of outcasts in the highschool dxd world. It has a lot of interesting character interactions and plot twists. Also, 'Gremory's Secret Legacy' is quite good. It delves into the hidden past of the Gremory family and how it impacts the present situation in the story.
I really like the 'highschool dxd gremory fanfiction' titled 'Rising of the Gremory'. It starts with a young Gremory character who is underestimated but gradually rises to become a very important figure in the high school. The story does a great job of character development. There's also 'Gremory's Redemption' where a Gremory character has to overcome past mistakes and earn back the trust of their peers in the highschool dxd setting.
Chapter 484, "Intercepting Attacks", is the clearest early answer because the buildup finally cashes out in a real clash. A useful checkpoint is the way the scene starts with The wind howled against Skylar's wings as Damien soared northward,... and follows through with But whatever they were, the world was about to learn something....
Chapter 80, "Outsmarting the Frost Wolf Pack", is the clearest early answer because it turns Shock Frost Saber's situation into a concrete plot event. It opens with How did we end up encountering a pack of Bone Spur Frost Wolves? and closes on Seizing the opportunity, Xia Hong abruptly released his right hand,....
Chapter 503, "Sleep In Peace I", is the clearest early answer because it turns Damien's situation into a concrete plot event. The chapter turns that into something concrete by moving from Jaws opened wide, lined with rows of jagged teeth dripping with... to This time, Damien skidded backward several meters, boots carving.... What makes it stick is that the chapter closes with "Fine," he said quietly.
Chapter 116, "Great Righteousness, Hunting Flood Dragons, Saliva [Five-in-One Mega Chapter]", is the clearest early answer because it turns Yuan Cheng's situation into a concrete plot event. A useful checkpoint is the way the scene starts with After passing the 500-meter perimeter, Xia Hong did not immediately... and follows through with The hunters are different, especially the five members of Luo Yuan in....
Chapter 384, "Separate Discussions And Discoveries", is the clearest early answer because it turns Damon's situation into a concrete plot event. A useful checkpoint is the way the scene starts with The moon was just beginning to rise, casting a silver sheen across... and follows through with You all are the real VIPs..
Chapter 336, "Second Phase Of The Second Test", is the clearest early answer because it turns Damon's situation into a concrete plot event. The chapter turns that into something concrete by moving from The arena had slowly but surely evolved into something unrecognizable... to Now they had nothing to protect..
Chapter 89, "【Seeking First Subscription】Chapter 89: The Limitations of Trap Hunting", is the clearest early answer because it turns Luo Yuan's situation into a concrete plot event. The chapter turns that into something concrete by moving from Two hours later, a Frost Wolf stepped onto an animal trap in the... to I want to see if these Cold Beasts really are endless." Unaware of....
Chapter 111, "Escape from Desperation [3-in-1 Mega Chapter]", is the clearest early answer because it turns Chen Ying's situation into a concrete plot event. The chapter turns that into something concrete by moving from After listening for a while, Chen Ying quietly descended, his waxy... to Chen Ying followed the sound and found a grown woman by the bonfire,....
Chapter 500, "Getting Information", is the clearest early answer because it turns Damien's situation into a concrete plot event. The setup is Its chest rose and fell in shallow, uneven motions, every inhale..., but the pressure keeps building through Its once-proud frame was broken, limbs bent at wrong angles, demonic....