Y/N POV

I was seated across from Sona, playing a game of chess with her. We've always been a challenge for each other but she usually always won, not that I cared.

Sona: Your Move.

Y/N: *Makes the wrong move* Is there a reason you made a move that could've easily led to your defeat?

Sona: Hmph~. *Smirks* Just testing your quick thinking skills. They still amaze me to this day.

Y/N: I see. I heard that Rias is dealing with her fiancée.

Sona: ... She was. She's now agreed to a rating game to attempt to escape it.

Y/N: ... She's going to lose, even if she trains.

Sona: *Sighs* I'm aware. I'm sure she only agreed to the rating game to prove that she won't be obedient to Riser.

Y/N: She always had that stubbornness, she's just good at hiding it.

Sona: True. Her decision to agree to it is... stupid in my head. Riser isn't afraid to cheat or to even kill, not to mention the Phenex Clan's accelerated healing factor and immortality...

Y/N: And yet he can bleed. That's all I'd need to kill him.

Sona: Oh? And will you do that?

Y/N: *Looks her in the eyes as they start another move* Let's imagine this chess board is the engagement party. All that's needed is to infiltrate the party, which will happen regardless due to you and your peerage undoubtedly being guests.... *Grabs one of Sona's Bishop pieces and places it to the side* All that's needed is to do is infiltrate a member of his peerage, more specifically, one with high magic concentration and someone who he's close to.

Y/Ravel: Someone who's family to him. *Puts the bishop piece to the side and replaces it with one of his pawn pieces*

Y/N: *Returns to normal* Once inside his peerage, impersonating his sister, I'll be capable of flanking him. Once that happens, I could shoot him in the head. This is all theoretical planning, of course.

Sona: Hmmm... While that plan is plausible... *returns the two pieces back to their respective positions* I fail to see how a bullet to the head will stop him due to his immortality.

Y/N: He's not invulnerable. He's only physically immortal. It's the psychological aspect of the attack that would damage his psyche and with the bullet to the head, it'll cause him to lose his mind, at least to some degree (assuming one of Rachel's blessed bullets will cause irreparable damage to his mental health...)

Sona: Hmm... and if things don't go as you planned it?

Y/N: If something were to go wrong, I'd lose myself in the crowd after creating a big enough diversion. From there, I'd attack from afar and if need be, occasionally in close quarters combat, picking off his peerage.

Sona: *Acknowledging sigh and smiles* You always have a contingency plan, don't you?

Y/N: "No plan survives contact with the enemy." Should my cover be blown, as a hitman, I must be prepared to take plan B.

Tsubaki: *Walks into the room* Sona, your sister is here.

Sona: ... *Sighs* Let her in... *Mutters* Please don't ask me to cosplay, please don't ask me to cosplay, please don't ask me to cosplay!

Y/N: *Playful* Oh~? Why not~? You're cute when you cosplay with your older sister~.

Sona: *throws a chess piece at him* I know I let you talk back to me but shut up!

Y/N: *Flicks it into the air before catching it with two fingers* I rarely ever actually tease people, I wouldn't worry about it.

I handed Sona's chess piece back to her as the door opened, revealing her sister, who was in a cosplay outfit.

Serafall: Hello sister~! It's been awhile~! *Looks at Y/N and turns serious but gives a faint smile and nods* Good to see you too, Y/N.

Y/N: Likewise, Miss Leviathan.

Serafall: *Goes back to normal* Oh don't be like that~! *GIF below* We're friends aren't we~? *hushed tone* Even if you are a hitman...

Y/N: Mm. *Acknowledging Nod*

Serafall: I never would've expected you to be such a dirty player to be honest, sister...

Sona: It May be unorthodox but Y/N's sacred gear and profession make him a perfect candidate as my pawn.

Serafall: I suppose you have a point but did you consider what might happen if word got out about his occupation? This could be damaging to the Sitri Clan. You know I'll support you until the very end, but you're walking a fine line that could end up with you exiled from the clan?

Sona: I understand, but sometimes you have to run before you can walk, sister. Sometimes, a stupid and risky move will lead to an absolute victory in a game of chess.

Y/N: *PIC below* (Did she...? Yeah, she quoted Iron Man.)

Serafall: Fair enough. Well, I just wanted to say hi... whatever you're planning, be logical. You're playing with your title as a Sitri and the possible lives of others.

Sona: I understand. I must prepare for being the referee for Rias' rating game.

Serafall: I understand. It was good chatting with you and your pawn. *Pats Y/N's head a bit*

Serafall then left via a teleportation circle, leaving Sona and I alone.

Y/N: I suppose I should stay and watch?

Sona: *Gets up and walks to the window* I don't need you to watch the rating game. We know how this will end. What I want from you is simple

Y/N: And that is?

Sona: *Turns to face him* Knowing is half the battle.

Y/N: Infiltrate the Phenex Mansion as a servant. Learn from them and use it the knowledge against them to better fight them?

Sona: Y/N. I owe Rias a favor and this is how I'll do it: I'll help sabotage the engagement party.

Y/N: ...

Sona: You, Y/N? I'll need you to do what you do best.

Y/N: What's that?

Sona: Hunt.