A few more years pass since your retrieval of the child, which prolongs the Emperor's life substantially. You are currently overseeing the construction of a new superweapon for the Empire - the Starkiller Base, a hollowed moon with the potential to destroy planets. Under your boot, the work progresses according to plan and schedule.
One day, your master arrives on the base to see the work being done for himself, and to speak with you privately. You:"My master, I hope you are satisfied with the progress being made here." Sidious:"Yes, Lord Xenos, the base is in order. however, that is not the only reason for my visit. There is another, one that will require your full attention." Y:"Yes, master?" S:"Years ago, you trained Leia, and she turned out well. But now, her daughter requires training. She calls herself Kyla Ren. The blood of Skywalker runs through her veins, and raw power like that needs an expert hand to lead it. You will go to the world of Vardos and show that Kyla the true nature of the Dark Side! Make sure that she is an obedient servant of the Empire, and that her training is in order. Can you do that, Lord Xenos?" Y:"Of course, my master. I will do as you ask, and leave immediately."
You board a shuttle, and travel to planet Vardos, one of the most loyal planets to the Emperor, thanks to renowned Inquisitor Leia having a residence there.
Stormtrooper commander:"Greetings, Lord Xenos. We are here to escort you to the palace. Inquisitor Leia is awaiting your arrival, come with us, please. Y:"Thank you, lead the way."
Troopers take you to the huge building at the center of the city, and you enter Leia's palace. You get inside the meditation chamber to speak with her.
Leia meditates in darkness, only the lightsaber illuminating her face. Leia:"Greetings, master. I was expecting you, the Emperor announced your arrival." Y:"Good to see you, Leia. Enjoying your retirement?" L:"The palace is alight, but I do miss the action. No rebels, no Jedi to hunt...I tried training my daughter in the ways of the Dark Side, but she has proven to be...difficult. She has a hard time controlling her power." Y:"That's why I'm here." L:"I know. She is waiting for you in the training room."
You make your way to the training room and enter. From the darkness, a masked figure emerges, staring you down. Kyla:"I suppose you are my new instructor?" Y:"Yes. I am Darth Xenos. The Emperor he's sent me to show you the ttue power of the Force, and to see if your powers are in check." K:"My powers may be greater than yours, Lord Xenos." Y:"That may be so, but they will not serve you well if you are unable to control them. The emperor wants to make sure that you are an asset, not a liability." K:"Enough talk. How about we face off, and then we can see who is that master." Y:"Your arrogance will be your downfall. Fine, let us duel!"
She ignites her saber, and you ignite yours. Her weapon resembles her - powerful, but unrefined. She advances and makes the first move, swinging her saber at you with much strength, but little finesse. You block her strike and counter, making her step back and block your attack. You keep fighting, but Kyla is unable to find a weakness in your technique.
Y:"You are unfocused! Impatient! You have to calculate your moves, see them before they happen, not just use your anger to strike blindly! Focus, girl!"
She roars at you and swings hard, but you step aside, making her miss and quickly swing back at her. Your blades lock and after some struggle, she uses her Force-push that almost knocks you down. Y:"Hah, not bad. But not good enough. If this was a real fight, I would have killed you ten minutes ago. You have the power, you have talent, but you are missing something. Hate and anger will only get you so far. There is a deeper source of power, one that you must unlock." K:"And I suppose you can show me what that is?" Y:"Yes. It is lust that can never be satisfied. The more you feed it, the hungrier it grows, powering you."