Imperial Prince Luke was Lord Vader's greatest pride and much beloved by the Empire. A bright and cunning man, the prince became his father's right hand in enforcing the emperor's will throughout the galaxy. He shared Lord Vader's skill in lightsaber combat, yet he was not cold and ruthless in the manner of his father; in fact, many of their enemies would come to vastly prefer meeting the prince in battle instead of the dark lord.
Contrary to what the rebels would have us believe, the prince was a strong advocate for justice and the welfare of others. He worked tirelessly to abolish slavery in the Outer Rim, bestowing especial favour upon Tatooine, and eradicated the Hutt Cartel among many other prominent crime syndicates. His philosophy was to rule with a kind hand rather than an iron fist; indeed, none could resist his benevolence in the end, and those that did would live to dearly regret it.
Here is Luke's official portrait as the Imperial Prince, also commissioned by Vader as part of the dual set with Leia's! This one is entirely based on George IV's 1821 coronation portrait by Thomas Lawrence; George has a sweeping black cloak in that one which matches Queen Victoria's portrait very nicely, so I went with it XD
I added Bast Castle to the background to indicate Luke's loyalty and closeness to his father. That's not to say that Leia isn't close to Vader in this AU by comparison, but I imagine she'd vastly prefer the brightness of Coruscant to the depressing lava world of Mustafar loll And, just like his sister, Luke reaches for his lightsaber to assert his dominance and power, especially with the Dark Side ;)
Here are some of my outfit concepts for Luke, mainly using sun motifs to complement Leia's moon/night designs! The third one was heavily inspired by Princess Irulan's dresses from Dune pt2, especially the beading; I really wanted to bring out that rays-of-sunlight look to his outfits while also keeping that "evil" vibe loll And his black cloak remains the simplest design, of course XD