This one-shot is based off Laivaaja's A03 story "Imperial Babysitters" it's cute 17-chapter story where they have posted Luke/ Vader art, it's really good so I recommend checking it out. This one-shot is based off chapter 14 "Choose A Star"

Brightest Star

One-shot

He hadn't meant to intrude, it was supposed to be a simple mission—straight in and then out, a relay of information and mission logs, but he stood transfixed by the sight in front of him, a moment of upmost vulnerability. He knew he'd be executed if he was to be seen spying, but in front of him lie a scene so—Human? So pure, an exchange of love in the most paternal manner. It shouldn't have shaken him to his core so much, it was normal—a father doting on his son, he'd done it before with his own children. But this wasn't a normal person per say, this was is superior—this was Darth Vader known throughout the imperial academy and navy as the most feared man in the galaxy second only to the Emperor himself, to work such a man was a guaranteed death sentence and a promotion even more so. Darth Vader was known for executing officers and slaughtering anyone who stood in his way of enforcing the emperors will, renowned for fury and the mechanical rasp of his respirator, it was hard to ever imagine that there was a living breathing human being behind such a tormented existence, it unnerved him to his core to see him act so humane? Display an emotion so different from the fury he usually enforced.

He watched, transfixed as the small infant placed his cubby little hands upon the sides of Vader's mask. "Fafa." He mumbled, tracing small patterns over the mask with his tiny fingers; seemingly transfixed and mesmerised by the ridges and sharp lines.

The dark lords artificial red lenses looked up from his datapad to stare at the infant held securely in his arms. Such a stare would cause Piett to panic—go over in his head the multiple scenarios in which he'd displeased his superior and how he'd be executed for it—but not this infant, who's large blue eyes stared back into the mask in intrigue.

"Yes, little one I am your father." He heard Vader reply, tracing a gloved finger down the infant's cheek to gently caress his cubby chin.

The infant giggled and pressed a saliva covered hand onto the control box of his suit. But the dark lord didn't hesitate—officers had there windpipes crushed for so much as looking at it and here this infant could touch it without zero repercussions. "Heart, Fafa heart." He babbled.

For a moment he hesitated, Vader pulled the infants hand off him and gently held him so that his tiny arms wrapped around the dark lord's neck.

"Do you know how much I love you, Luke?... more than there are stars in this galaxy." He muttered to the infant. Piett found it frightening rather than endearing, here a tiny infant sat in the arms of the second most terrifying being in the galaxy and cooed as he professed his love for his son. It was such an unbelievable scene that he'd almost wondered if he were still asleep—it was so utterly inconceivable to imagine Darth Vader as having any other feelings other than resentment and rage, and yet, here he was behaving in such a human way. He almost felt ashamed for snooping, I felt as if he'd just invaded something private, walked in on something terrible, something he never should have seen, yet at the same time he couldn't bring himself to look away. He felt ashamed at seeing Vader at his weakest, all shields dropped, and animosity forgotten all so that he could see the beaming half toothed smile of the infant sat in his arms—no—not infant, Vader's son.

How was he conceived? was Darth Vader even able to conceive children? Surely, he was, otherwise this child would've never been born. It wasn't within Vader's character to ever bother himself with adopting a child but then again, he's never expected his superior to show such an affectionate display—He'd heard the rumours of Vader's rebirth. A man so horrifically scarred and mutilated, forced to wear a mask with a terrifying rasp because children wept at his face until there eyes bled.

"Swars?" Luke mumbled back.

Vader placed a gentle hand to the soft fragile nape of his son's neck and almost seemed to beam with pride. "You are such a clever little one." He praised, stroking the small head where white thin locks developed.

Luke leaned into the caress and cooed incoherently, saliva dribbled down his chin and pooled at his neck, soaking his clothing.

He continued to caress the locks "Pick any star and I will give it to you, little one. Choose them all if that is what you wish." Vader said through the harsh baritone of his voice modulator.

Luke beamed; his small teeth poked out from under his gums "Fafa swar." He babbled back, pointing a handout into the vast void of space, identifying the brightest star. "Dat swar Fafas!" he exclaimed.

Vader stared at the star for a moment, several rasps of his respirator were the only sound Piett heard. "No little one, that is not the star I've chosen." Vader replied.

Piett watched as Luke's lip wobbled "Fafa no swar?" he protested.

He pressed his mask against Luke's head as if to kiss it "You are my star Son, I cannot pick another, they are all dull in comparison to you." Vader explained.

Piett smiled and placed the stack of Datapads on a desk in front of the door, he'd outstayed his welcome. He quietly shuffled away and took one last look back at the scene behind him and froze, Luke's large blue eyes stared into his in curious wonder. He placed finger to his lips and quietly left.

His perspective forever changed.

Just a little fluffy Oneshot, please do tell me what you thought of it, I do very much enjoy your feedback.