Detention with the butterfly pin

What does that mean?

It was night and Severus was sitting by the window of his dorm, it was late at night but Severus couldn't fall asleep, not after that letter.

He was trying to read a book but couldn't focus, his mind was a mess. Then all of a sudden, he feels someone's arms around him.

Mulcibier.

"Clingy one are you?" Severus says scoffs, though he leans his head back in Mulcibiers shoulders.

"Why aren't you in bed, Yeobo?" Mulcibier whispered sleepily, he had a habit that when he wasn't fully conscious or sober he started calling Severus by terms of endearment of different cultures.

"..I just can't sleep..." replied Severus, closing his eyes as to quietly savor this moment.

"...did that man-?" Mulciber started but Severus interrupted him.

"No don't worry about it..." Severus said, Mulcibier knew he was lying but didn't say anything.

"If it can't sleep... that perhaps and can sleep beside you so you're not alone?..." Mulciber sheepishly asked

(Next paragraph is a metaphor I guess by me)

You see the reason why they were so close is because 1st year Mulciber was touch-starved and had no light in the empty hole that was called his heart, it was just filled with darkness. While Severus was also touched starved, and while Severus's heart illuminated light he could give to people, like he did to Lily, there was no light in his own heart, just hollowness, and so once they both bonded with one another, the darkness from mulcibiers heart seeped out and turned into light, which then filled Severus's heart, and Severus's illumination light filled Mulcibers heart, and slowly they held and healed one another, slowly to this very young day.

(End of metaphor)

Severus sighed half content half exasperated, a mix of black and white that is now grey.

"And what if-?" Severus starts.

"And what if Regulus comes in?" Mulcibier finished his sentence for him.

Side story, when Regulus first came to Hogwarts as a first year he was very scared of sleeping alone. And so he met 3rd year Severus and they bonded well, and ever since then, Regulus weekly sometimes daily came over to Severus's dorm, saying he had a nightmare and only sleeping next to Severus would make the nightmares go away, so Severus just smiled and let him come in. End of side story.

"You know that if Regulus was coming then he would've been here already, so allow me this one night to be with you, yeobo?" Mulcibier said, if there was one thing about Severus mulcibier didn't know then that would be that Severus absolutely couldn't refuse Mulcibier when he called him by terms of endearment, simply because he saw it as far too precious.

"...fine but only for tonight." Said Severus, the other male smiled and carried him to bed, lay them both down on his bed, got close.

"Good night mi amor..." Mulcibier murmured before falling asleep.

"Good night to you too..." Severus muttered back, and as he feel into unconsciousness, he wondered,

What does that mean?