Answers to reviews:

Guest: Hmm...

ChaosTOAOAA: Here you go.

Kamigawa Nagamaki: Yeah, I'll admit I was inspired by the Naruto version, but that could've used a little more work to be honest. It was a good story, shame it hasn't been updated in about ten years.

KingInTheNorth27: Thanks.

abyssjumper: I think it's best I just go through stuff all the way up to canon rather than doing a flashback. Much as that would work, I feel it's more fitting to actually show and do arcs before the events of canon began.

Guest: That will take a while, but I do have some picked out.

professorpoopypants00: Thanks.

JimmySG0: I'm hoping to do them right.

TwinstarDragon: Here you go. Sorry for the wait.

FanficCrossoverMaster15: The idea does have merit, though it would take a while for them to fall in love of course.

Thicc-Chungs: No.

Disclaimer: I do not own High School DxD. I only own the OC Damian Mammon-Lucifer.

'I hope Grayfia likes the ring. Diamonds are a girl's best friend, right?' Damian Mammon-Lucifer, grandson of the original Lucifer himself, thought anxiously as he entered his home, built by his own hands for himself and Grayfia. Clutched in his right hand was a small box, containing a ring, but not just any ring... an engagement ring. His nerves were showing given how tightly he was gripping it. Thankfully, he wasn't holding it tight enough for his Devil strench to crush the box.

Was this how his father felt before hr proposed to his mother?

He had been with Grayfia for about a year now, the two having met during the civil war and their love took off from there. It may have been a year, but Damian felt ready to commit himself to Grayfia by asking her to marry him. Some thought it was a little fast, but Damian didn't really care, especially with arranged marriages floating around lately and that was one thing Damian did not wish to become involved in given his status as the heir of both the Lucifer and Mammon Clans, the latter having been raised from a simple Extra Demon Clan to a House of the remaining 72 Pillars after the civil war.

And since Damian was the sole child of the lord and lady of both Houses, he was the heir of both of them, even though they were merged and acted as one rather than both. But Damian took pride in his last name being Mammon-Lucifer. His mother was Sarlith Mammon, and his father was Raylix Lucifer, so it was more of him paying homage, tribute and respect to his parents by using both of their last names.

Closing the door, Damian was about to call for Grayfia when he frowned as he spotted an article of clothing on the floor, one of Grayfia's tops. He crouched down and picked it up, raising an eyebrow.

"That's odd." He said. "Grayfia's not one to leave a mess. She always gets onto my case when I so much as leave a sock on the floor."

His frown deepened as he saw a trail of clothing, as the shirt was followed by shoes, and then blue trousers. He followed the trail, his heart beginning to beat with fear as he saw clothing that belonged to a male. Clothing that did NOT belong to him. The dread in his stomach grew as he heard something up ahead... coming from the bedroom.

Slowly approaching, almost praying, which would be ironic since he's a Devil, that this was not what he was thinking and that Grayfia was just playing a game to tease him, Damian approached the bedroom door and reached for the handle but he noticed it was slightly ajar, so instead he placed his hand on it and gently pushed it open. The sounds became more clearer now... they were moans! Sexual moans!

And the sight within made his eyes widened, and the words that followed made his grip on the ring box slacken, with it falling from his grasp.

"Grayfia..."

"Oh Sirzechs~"

There, in bed together, naked and clearly having sex... was Grayfia, the love of his life, along with Sirzechs, his best friend and brother in all but blood.

The tears began their flow down his cheeks as his heart shattered into a million pieces... and his hands slowly clenched into fists as anger and rage built within.

And when he got angry... his power made the tempature drop.

"Did it get colder in here?" Sirzechs asked as Grayfia moved on top of him, but she stopped at his question.

"I think so, but why did..." Grayfia looked around, freezing when she saw Damian standing in the open doorway, looking at heart with betrayal; and heartbreak. "Damian..."

Caught, Grayfia and Sirzechs quickly covered themselves as the silver-haired woman looked at Damian with an apologetic look, her heart shattering at the heartbroken expression on his face. SHe went to say something when she saw his expression darken with rage upon looking at Sirzechs, and his power skyrocketed.

"Damian! NOOOOOO...!

Year: 1274 (737 years before Canon begins)

Six months before Mongol Invasion of Tsushima

"AHHH!" Damian snapped awake and shot his hand out, a blast of darkness shooting out and completely obliterating a tree, leaving a scorched, burning mess in it's wake. The Devil breathed heavily as he glared at nothing, before he managed to relax as he realized where he was and that what he saw was just a ... dream. Or rather, a reminder, a memory, of why he was in exile in the first place.

The grandson of Lucifer leaned back against the tree trunk that was his pillow for all intents and purposes, while the small campfire provided some source of light in the darkness of the night, with the full moon yet to wane. Damian stared up at the night sky, looking at the stars, a couple of tears beginning to flow down his cheeks at the emotional wound reopening after only five months since he went into exile.

Five months since he found his best friend fucking the love of his life.

He knew his decision would've hurt his parents, especially his mother. She did everything to try and get him to open up after the betrayal, but he had been consumed with the desire to maim and kill Sirzechs leading up to their fight. And when he lost the fight... he could not stand being in the Underworld, watching Sirzechs and Grayfia be happy together, knowing what they did, what they've done. While he knew he will have to go back one day... that day would not come for hundreds of years if Damian had his way.

Damian shook his head and stood. He had dozed in this area for too long, it would be best if he got moving. With any luck, he'll find a small village or settlement nearby. But seeing as this was Japan, and he was near the territory of the Youkai Faction, who had a tense relationship with Devils, he was not banking on receiving a warm welcome if he came across the Youkai.

Damian kicked dirt over the fire, engulfing the little camp into pitch black darkness, but that was no problem for Damian who could see in the dark. He turned and walked away into the night.

His pace was calm and moderate, as he listened to the sound of the nightlife. All nocturnal creatures of the night were out and about, though predators did not attempt to attack Damian as they most likely sensed he was a predator in his own right. He may not be a Vampire of a Werewolf or something along those lines, but he was still dangerous.

He was only maybe two hours into his walk, with the only thing he's seen being nothing but trees, when his hearing picked up male chatter followed by the smell of something burning. He frowned and followed it, his eyes now spotting a faint glow that could only come from a campfire.

When he was close enough, he stayed within the darkness of the treeline, his eyes on the camp and his expression soured just a little when he saw who the ones responsible for the chatter were.

Fallen Angels.

'What are Fallen Angels doing so close to Kyoto? So close to the heart of the Youkai Faction?' Damian thought to himself with a frown. It was not uncommon for a supernatural creature to come into the territory of another, but Fallen Angels weren't exactly known for being likeable by the other Factions, especially the Youkai. Damian was sure there was a ban on them entering Youkai territory after an assassination attempt on one of the noble Youkai's children.

Damian didn't really know, nor did he really care at the time... and still doesn't.

'Not my problem.' Damian thought as he turned to leave, no care for whatever the Fallen Angels were doing, when one of then spoke up.

"Alright boys, I think we're far enough away to let the little princess... spend some quality time."

Damian paused and turned, his eyes narrowing as he noticed set-up tent. One of the Fallen Angels went in and came back out,l dragging a struggling, young blonde-haired woman with a voluptuous figure. Her hands were bound, as were her feet, but what caught Damian's attention the most were here bound nine tails.

She was a nine-tailed Kitsune!

Damian watched as she was dropped in the center of the camp, with the leader of the group chuckling as he stood over her. "Well, well, well, this is quite a sight. The princess of the Youkais, on her knees before me. Anybody can get ideas."

The kitsune glared up at the Fallen Angel. "Go fuck yourself." She spat definitely. Damian had to commend her on her strong spirit and will.

"Oh, we'll be fucking something tonight, alright." The Fallen Angel chuckled lecherously as he eyed the woman up and down, earning chuckles from his boys. "Alright boys, plan out your holes. I've got the pussy."

"I've got the ass." Another said with a grin.

"Her mouth looks inviting."

"So do those tits."

The woman glared at them all before yelping as she was pushed onto her back, and the Fallen Angel began gripping her cloth. "No! No! Get the hell off me! Stop!"

"Shut it, you little slut!" The Fallen Angel growled as he raised an arm to slap her.

"Let her go."

Everyone paused at the new, unknown voice and looked to see Damian standing in the firelight with a sword in hand. The sword was a silver-colored longsword. The blade is long and double-edged, with the forward-facing edge curving outward to form the guard. The handguard is is designed to resemble a vortex that reverses at the center of the handguard. The pommel carries a round piece that almost resembles a face. The sword's name was Mortem, which was Latin for 'Death'.

"The fuck?" A Fallen Angel frowned.

"What's a Devil doing here?" Another sneered, summoning a Light Spear.

The lead Fallen Angel scoffed as he stood and summoned a Light Mace, striding towards Damian. "Tonight just gets better and better."

He swung the mace but Damian blocked with his arm then drove his sword through the Fallen Angel's right leg and ripped it out, severing the appendage from the knee and causing the Fallen to scream as blood gushed out the wound. The other three Fallen Angels rushed to attack, but Damian was quickly on the offensive as he kicked one in the face, sending him stumbling into the campfire which set him ablaze and he screamed and thrashed on the ground.

Damian ducked a Light spear from another Fallen and stabbed him through the chest while kicking the other in the stomach before giving him an uppercuyt, then he dragged his sword upwards, slicing the Fallen Angel's face into two halves. He watched as the final Fallen Angel groaned and got to his feet and approached, then kicked him into a tree.

"What were you doing here?" Damian demanded in a low tone.

"W-What?" The Fallen Angel blinked at him. In response, Damian stabbed Judgement through the Fallen Angel's right arm, pinning him to the tree. "AHHHHH! OKAY! Okay! We-We took her because we thought she might be worth a good price!"

"And the near rape attempt?" Damian asked with anger in his eyes.

"W-Well... have you seen her?" The Fallen Angel chuckled. Damian snapped off a branch and impaled it through the Fallen Angel's stomach, wrenching it tightly while ignoring the blood-curling screams of his prey. Damian turned and picked up a nearby log, examining it as the Fallen Angel gritted out in pain. "W-W-What are you doing?"

Damian looked at him darkly. "I'm going to find a home for this."

"NOOO-!"

With a roar, Damian drove the log directly into the Fallen Angel's mouth and punched it repeatedly, breaking the mouth and splitting the skin apart as the Fallen ANgel's mouth was mangled. Damian took out what was left of the log and brought it into the Fallen Angel's face repeatedly until there was nothing but a bloody mess left, and he tossed the log aside, ripped Judgement out the corpse before turning to the gaping, bound kitsune who had watched the whole confrontation.

Damian silently approached her, causing her to back up, but he crouched to a knee and cut her bindings with his sword before standing as his weapon disappeared in a flash of dark light.

"T-Thanks." The woman thanked him quietly. Damian simply grunted and turned to leave. "Wait!" He stopped. "You're just going to leave like that?"

"Kyoto's not that far away from what I've heard. I'm sure you can make it back on your home." Damian said coldly.

"Yeah, but... you save me from being raped and are just going to walk away?" The woman frowned as she stood, brushing dirt off her clothes which Damian noted looked regal on her, a sign of nobility. He would know someone of noble standing when he saw one. "I should reward you."

"I don't need anything." Damian said as he turned to leave when suddenly several Youkai jumped out of the darkness and surrounded him.

"Halt, Devil!" One of them ordered, the tense Damian looking around. "Lady Yasaka, are you alright?"

'Yasaka?' Damian's eyes widened a little. 'Isn't that the name of the princess of the Youkai Faction?'

"Yes." Yasaka nodded. "But please, let him-"

"Yasaka!" A male voice called as an older man with some similar features to Yasaka arrived, hurrying over to her quickly.

"Father." Yasaka breathed and hugged him when he was close.

"Are you hurt?" The man asked, checking her for any injuries.

"No, I'm fine. Thanks to my saviour here." Yasaka gestured to the silent, watching Damian as Yasaka's father turned his attention to him and frowned a little before he gave a slight bow.

"Though I do not have much fondness for Devils, I am grateful for your aid." The man said.

"My Lord, he could be with them." One of the guards said, looking at one of the corpses. "He could've killed them to make himself appear innocent."

"He didn't!" Yasaka stepped in, turning to her father. "Father, these Fallen Angels tried to rape me! It's only because of him that I wasn't robbed of my virtue."

Yasaka's father was silent as he stared Damian down, the Devil staring back. After a few minutes, the man nodded. "I know when my daughter is telling me the truth. However, I can't allow a Devil to wander my territory as he sees fit. The last time I did... " He shook his head. "Bind him. We'll take him back to Kyoto and he can explain himself there."

"Father..." Yasaka began.

"Enough, Yasaka." Her father said with a sterner tone before it softened. "I know he saved you, but I can't allow him to roam unchecked without knowing his intentions. Until I am certain of them, we have to keep a close eye on him." He looked at Damian who was annoyed as his hands were tightly bound. "I trust you won't resist?"

Damian glared. "Not like I have much of a choice unless I want the whole Youkai Faction after me."

"Smart boy. Never thought your kind could be smart." The older kitsune chuckled, earning a look from Damian before he grunted as he was pushed forward to follow Yasaka and her father.

'What have I gotten myself into now?' Damian thought with a sigh.

And that's it for this chapter. First off, so sorry for the long ass wait, it was not easy trying to come up with the second chapter. But I'm hoping this proved alright at best. I do apologise if it's not the best work I've done, but at least it's something. So yeah, Damian's near Kyoto, has met young Yasaka when she's a princess. Now, appearance wise, she'll look at least in her early twenties, not close to her canon appearance yet as she's still young but getting there.

Harem: Yasaka (Alpha and main girl), Kuroka, Serafall, Irene Belserion (Fairy Tail), Raven Branwen (RWBY), Akasha Bloodriver (Rosario + Vampire), Chisato Hasegawa (Testament of Sister New Devil), Celestine (Kuorinu), Olga (Kuroinu), Chloe (Kuroinu),