Disclaimer: I don't own High School DxD or it's related concepts and characters, but Ichiei Ishibumi and his affiliates do.
A Pair of Wannabe Playboys
With nothing new and/or exciting happening in the Underworld at the time, Riser Phenex, the third heir of the Phenex Clan, decided to pay the Human World a visit out of wistful curiosity. While he preferred the Underworld for numerous reasons, he did found gazing at the oceans of Earth to be a good pastime, especially when there were attractive women in bathing suits nearby. After having his fill of eye candy at a Japanese beach, Riser then went to Kuoh Town where, after bothering his arranged fiancé, Rias Gremory, at her school, bought a hamburger for his lunch and decided to walk around town to enjoy the more natural scenery before heading home. However, by the time he believed that he had his fill of Earth for a day, he then saw something that caught his attention.
In the Kuoh Town suburbs, he saw a nearby collared cat on a sidewalk limping with it's left foreleg as an apparent result of colliding with a wall. Riser, for all his arrogance and lust, felt sad for the poor animal, and seeing that he had a vial of Phoenix Tears at hand, already began to walk over to offer help before a Human youth approached it first.
"Hey, little girl, are you okay?" The brown-haired teenager said to the cat in concern. Quickly gesturing for the cat's trust, the boy then placed his arm near the wounded foreleg before a pair of silver rings appeared on his finger to emit a green light that then healed the cat's injury.
Riser's eyes widened. He went to the Human World to divert himself from his boredom and found a wielder of Twilight Healing who knew what he was doing. While he wanted his peerage to consist of his little sister Ravel as well as his own harem, he wasn't blinded by his imagination to the point that he would dismiss the benefits that such a Sacred Gear would bring to himself, his peerage, and the Phenex Clan as a whole. Making up his mind, Riser then approached the brunette when he sent the healed and grateful cat on her way.
"That was quite a noble deed you did, kid." He called out to him.
The teenager turned to Riser and narrowed his eyes, as if in recognition of a potential threat. "What's a Pureblooded Devil doing here?"
Riser chuckled, not surprised the kid already recognized him as such. "You don't have to worry, Riser Phenex is not here to cause trouble. Riser was in the neighborhood and saw you work your magic."
The teen relaxed a bit and forced a smirk at Riser. "The Phoenix Tears family, huh? Ddraig told me about you once when I was first practicing my healing power."
Riser's eyes then widened again in recognition of the name. "You know of the Red Dragon? How?"
The kid then showed his arm to manifest a red gauntlet. Smirking wider at Riser's disbelief, he then said. "Nobody said you can only have one Sacred Gear, right?"
His astonishment given way to amusement, Riser replied. "Very impressive, young man. Riser wants you in his peerage even more now."
The kid narrowed his eyes again. "What kind of peerage?"
Riser scoffed unamused and disgusted. "Relax, boy. You're definitely not my type, I just think your skills could be useful to me in the long run."
The brunette shrugged. "Understandable. How about this? I'll join your peerage, and in exchange, you'll lead the way for me to have a harem of lovable women of my own. My name is Issei Hyoudou by the way."
Riser got his amusement back and held his hand out to shake Issei's. "Glad to see you've got good tastes, Issei."
Taking Issei to the Underworld with him, Riser led him to his family castle. There, Issei would be officially reincarnated into a Devil as member of Riser's Peerage. However, when Riser's younger sister Ravel questioned Issei's strengths and worthiness to take what would've been her spot in the peerage, Issei himself was more than happy to demonstrate by fighting Riser himself. Riser was more than confidant that Issei wouldn't stand a chance against him, but failed to take into account that Issei had trained himself for a considerable time.
One boosted straight punch was all it took to beat Riser back and leave the rest of his peerage and family stunned. To show that there were no hard feelings between them, though, Issei was quick to use Twilight Healing to get Riser back up.
"Uh, well, that happened." Riser forced himself to say while still in shock over his defeat. Turning back to Issei, he then said. "All right, Issei, how about we get this over with in the next half-hour? I think need to work through this."
Seeing Riser walk away with his father, Issei shrugged with a smile at Ravel and Lady Phenex. "Well, he could've taken it worse. So, how do you think of my strengths, now, Miss Ravel?"
Seeing Issei's bright smile directed at her, Ravel blushed which didn't take go unnoticed by her grinning mother. "That was impressive, Mr. Issei."
"Please call me Issei." Issei replied before noticing Ravel's blush. "Are you okay?"
Lady Phenex chuckled. "Oh, don't look now, young man, but it appears you caught my daughter's fancy."
Issei looked genuinely shocked while Ravel stammered in denial.
"You two can kiss already, if you want." Lady Phenex teased which made Issei blush as well.
"That's crazy, Lady Phenex." Issei eventually said. "What could a beautiful girl like your daughter see in someone like me, anyway?"
Ravel's blush deepened after hearing that comment and in that moment, decided to roll with it. "All right, just this once."
"What?" Issei asked before finding his lips captured by Ravel, an action he eventually returned.
Felt a bit disappointed that I hadn't got any reviews for my Dragon Ball one-shots at the time I started writing this, and when I was looking things up on the High School DxD wiki, I had a thought of how I could do my first High School DxD fanfiction as a one-shot. If you've seen my other one-shots from One Piece and the rest, then you should know that this one-shot and those like it will explore the idea of the main male protagonist having a different or secondary canonical power fitting the series he's in alongside a canonical love interest or so that fits the situation the one-shot takes place in. In this case, Issei Hyoudou is one of the eight Twilight Healing wielders in addition to having Boosted Gear and finds himself joining Riser Phenex's Peerage as a Bishop in place of Ravel after a chance meeting with Riser himself. Not quite the usual thing you see in fanfiction so far, even if Issei has joined a different Peerage with or without a different, or more than one Sacred Gear, huh?
I admittedly took some leeway, though, for simplicity reasons, but I hope you liked it well enough. Also, for those who've seen my Gundam writings, I should probably say that I've decided to scrap whatever tentative plans I had for a SEED/UC crossover, a Wing/00 crossover, and a Wing time travel story/challenge. Kind of disappointing, I know, but I couldn't really find a good explanation for time travel could work in the Wing universe, considering the people there are more normal compared to the typical Newtypes, X-Rounders, Innovators, and Coordinators with the SEED Factor you might see in other shows, and as much as I like a good, reasonable crossover, finding a good excuse for interdimensional travel, while not as hard as making a composite, is still hard. Speaking of Newtypes and Innovators, perhaps I can think of time travel ideas for those fandoms featuring Setsuna in The Armed Interventionist of Time and Uso in The Universal Century's Last Hope for Peace respectively.