A/N: To the reader who left a comment about the convenience of a magical book in a small town library... Thank you for the input, it really forces me to think. This chapter is going to be a bit dialogue heavy because of explanation. I also apologise ahead of time if this chapter seems jumpy, dialogue is the weakest part of writing my writing skill. It's also because(spoilers) of the new character and how unsure I am of how he should be interacting with everyone. :P

"Star! What are you doing?" Marco said, still shocked.

"Oh, come on Marco! It's not like we haven't kissed before." Star said, grinning ear to ear. "I'm just glad you're okay."

Marco just casually rubbed his neck. "Yeah, but we've never kissed in front of your parents."

This was no revelation as Queen Moon had nearly dropped Marco's book and King River was now dancing in circles mumbling "I knew it" over and over. Moon recovered from her shock and looked over at the young couple. "Are you sure he's who you want, Star?" Her voice was filled with concern.

She looked at her mother and nodded, then gave a thumbs up. "Yup, and he knows what it means already."

"Right, before things get too awkward... I see you've figured out the book, young lad." A voice from the shadows interjected into the conversation. It belonged to a man in a smoke grey robe who slowly stepped into view, hands in the air. "My name is Johan Keeper, and it is my duty to find and train the magically inclined before disaster strikes."

Marco had trouble making heads and tales of the situation and it was pretty obvious he wasn't the only one who felt confused. Everyone else had paused to stare at the new figure.

"Yeah, a likely story." Star raised her wand at Johan. "How do we know you're not one of Toffee's monsters come to kill Marco again?"

The man sighed and pulled back his hood to reveal the face of Echo Creek's old librarian. "I think this should be evidence enough for you, young Princess Star Butterfly."

"You're definitely don't look like a monster but how do you know my name?" Star asked, no less tense than before.

"You really think I wouldn't be keeping tabs on all of the magical goings ons here? It is my job, after all." He replied.

This answer seemed to satisfy her enough to make her drop guard. "So, Mr. Keeper. What do you want with Marco?" She also wanted to ask what book he meant but figured it was probably the one her mother was holding.

"Yeah, what do you want with me? I just got that book from the library-" The realization hit him. "That's no ordinary library, is it?"

"Spot on, kiddo. You catch on quickly." Johan clapped. "My family line has been in charge of managing all of the magic items and finding those who would be wielders. We set up a library as a trial of sorts to vet out the non-magical. You passed and now the duty falls to me to train you."

"Hold on, trial? This doesn't make sense at all. I mean- I get the magic part because Glossaryk taught me the basics but, all this 'family duty' stuff sounds way too convenient." Marco started to rant. All eyes in the room were on him as he paced.

Star attempted to say something but Johan cut her off, offering more explanation to Marco. "My family was the first to be contacted by the Mewmans. Hundreds of years ago they brought their magic here, giving us items imbued with charms and encrusted with jewels that helped enhance our potential. Your book is one of those items. It's called 'The Book of Need' and always contains what knowledge will be most useful to its master."

At the mention of this, Queen Moon flipped open the book and tried to read the contents to confirm. "All nonsense, the book is just full of random characters. Regardless, it still is written in the ancient dimensional text." She made it clear that there was only a limited trust in Johan's words.

"Ah, about that... The only one who can read it is the person it chooses as its master." Johan gestured to Marco. "In other words, it only reacts to him."

"I'm still confused, but can we resolve this tomorrow? It's late and we don't know when Toffee could show up again." Marco complained.

Star, King River, and Queen Moon all nodded in agreement with Marco. Everything could be talked over tomorrow, including the connotations of Star kissing Marco. Moon pulled out her dimensional scissors and cut a portal to the courtyard.

After all had stepped through, River spoke up. "Johan Keeper, you can take one of the guest chambers. Marco, you can stay in Star's chambers."

"River!" Moon exclaimed, very displeased with the suggestion.

"What? If they're mature enough to kiss, then they are mature enough to share bedchambers.

Moon sighed and contemplated for a moment. "Alright, but we will be holding a serious discussion about this tomorrow."

Star and Marco looked to each other and blushed heavily. What were they expected to do? Both their thoughts were racing, filled with fantasy of what could take place on those velvet bed sheets.

A/N: If you have a problem with me adding Starco lemon to my fic or are not old enough to view adult oriented content then you may want to skip to the end. You've been warned!

Marco snapped out of fantasizing first. "Uh, Star? Where'd everyone go?" They were completely alone out in the courtyard of the Mewni castle.

Star didn't reply at all. Instead she started to gnaw on her wand and mumble and moan lightly. Her face turned a deep red and the hearts on her cheeks started glowing faintly. "Marco, don't- Not there..."

After hearing that, Marco grabbed Star's hand started dragging her through the castle to her room. As they progressed, he tried to rationalize his thoughts. It was only natural for a boy to have at least some fantasy regarding a magical princess from another dimension, right?

They made it to Star's door and the guards held the door open for the two. Never had he felt more embarrassed as he dragged a blushing, uncontrollably giggling princess into her bedroom. She just looked so cute with her fantasy expression and he didn't know if he could hold himself back, but he had to try.

The door slammed behind the couple and Marco had to splash Star with water to get her out of fantasy land. "I'll sleep on the floor." He told her.

Her reaction was to throw him onto the bed and jump on him. "Not gonna happen! We're sleeping together tonight, Marco!" She yelled out excitedly.

Marco's thoughts were racing, he could feel where she was sitting and it wasn't good. The resolve of the future king was fading quickly into the horizon as a dampness soaked through his jeans and boxers. "Wait, Star! Think this through!" The last thing he wanted was to go too far and hurt her.

Star giggled and proceeded to kiss him. "I already have," She proclaimed joyfully. "And I like where this is going!"

Everything went still in Marco's mind. "Then- You're okay with having sex with me? What if I hurt you?"

"Don't be silly, Marco. You won't hurt me." She smiled and kissed him again. "Now let's do something about all these clothes."

Marco fumbled about, trying to undress without falling off of the bed, then helped Star undress. As he pulled up her dress, he noticed something odd. She was commando. No bra or panties. "Uh... Star? How come you're not wearing any underwear?" If Marco wasn't blushing before, he sure was now.

"Well~ I was kinda expecting this to happen tonight, so I thought I'd make it easier on you." She explained, picking up where Marco left off in disrobing her.

He opened his mouth to speak but nothing came out, his mind was too occupied with the beautiful sight of Star naked before him. It was taking everything within his power not to just pounce on her and live out some fantasies.

The look on his face said everything to her. "It's okay, Marco." She fell back into the pile of pillows atop the velvet sheets. "Give me a night I'll never forget."

Marco carefully climbed on top of her, his hands shaking. This was both of their first times, so how could she be so calm about it? All he knew about sex was a basic talk from his parents and what he'd seen on the internet. Maybe he was so nervous because he didn't want to spoil things with Star. "You sure?" He asked with a shaky voice.

"I'm sure." She wrapped her arms around him in a loving embrace.

Where to start... Marco began recalling the steps for foreplay he'd read online. First: Kissing, use your lips and tongue to tantalize her erogenous zones. Start on her lips and move slowly down to her breasts. "Okay, you've got this." He mumbled to himself, starting out with a deep kiss.

As Marco worked his way down to Star's breasts from her lips, he could feel her breath becoming heavier. Did that mean she getting turned on? Time for step two: Use your hands to massage her breasts as you move down to tease her clit with your tongue.

"Marco..." Star exhaled, breath shaky. She was biting her lip in effort hold back further moans but it was fruitless, Marco's tongue just felt too good on her clitoris. The combined stimulation of her breasts and clit was enough to make her arch her back and moan loudly as she went over the edge.

"Star, did you just cum?" He asked, a hint of smugness tainting his voice.

She looked away and blushed violently. "Maybe..." Suddenly Star took the lead, pushing Marco down on his back and crawling between his legs. This was her first time seeing a fully erect penis. It was much bigger than she thought it would be, much to her pleasant surprize. She began lightly rubbing the tip with her thumb.

It was Marco's turn to try and stifle his moans. Having someone besides himself rub his member was completely different than when he did it solo. The sensation was a whole new level of of pleasure. If this was just foreplay, how much better would the real deal feel?

Star had worked up the courage to lick Marco's tip and gradually take as much of his penis into her mouth as would fit. At this point she couldn't keep herself from sliding a few fingers into her vagina, following the rhythm of her sucking.

"Star," Marco started to tense up. "I'm- Gonna cum!" He called out between breaths. His hips bucked as he tried to hold out. It was only a few seconds after the warning that he came to orgasm, filling her mouth with his load.

Star sat up and offered a surprisingly sexy half-lidded stare at Marco as she swallowed his seed. "So this is what it tastes like... I want more!" she licked her lips and tried to crawl on top of her betrothed again.

Marco was able to regain his thoughts before she pinned him down. "I think that's far enough for tonight." He sat up and placed his hands on Star's shoulders. "We're going to have a long day tomorrow and I'm worried about taking things too far tonight."

Star's eager and lustful look faded to that of dejection. "Was I not good enough for you? Do you not want me?" She was nearly in tears.

"No, it's not that. I do want you, and I'd love to go all out tonight but I feel like it would be better to work up to that." He pulled her into a loving embrace. "So we can get to know each other more intimately and figure out what we do and don't like sexually, you know?"

"Yeah, I guess that makes sense." She hugged him back. "It's just... I'm worried about losing you. Especially with what happened earlier." Her grip tightened on him.

"I'm not going to leave you." Marco fell back into the pile of pillows, pulling her down on top of him. "Besides, If I try to run away it'd be treason." He teased.

They both giggled and cuddled together before exchanging tired 'I love yous' and falling asleep in each other's arms.

...

Marco was first to rouse from slumber. In his drowsy state it took him a moment to notice that his head was nuzzled right between Star's breasts. What had happened last night? Did they have sex? A knock at the door only served to increase his panic. He couldn't even muster a voice to answer.

A few agonizing seconds passed before the door bolt slid open and none other than Queen Butterfly walked in. "It's time for you two to get up, King River is waiting in his chambers for us." Her tone made it clear that she wasn't happy with the situation.

A/N: I know a lot of you are going "Woah, wait a minute! It's only been a day since they got together. Isn't this a little too fast?" Eh. If you consider that they've practically been dating since maybe a week or so of her being on Earth(Minus the Jackie stuff) and probably have a lot of repressed desires, then not really. I also know a lot of others are going, "Hey, aren't they a bit too young for that kind of a relationship?" For you, I now present to you why I have no problems writing lemon of Starco.

In this fic's cannon Star and Marco are betrothed, so

I feel like it's necessary to the progression of the story.(Moreso later :P)

In Mewnian law, both parties are likely of age.

In actual law, as long as the characters are fictional it's not illegal.(US law. I don't know about other countries, though.)

I hope this is reason enough for concerned readers to understand why I chose to add in such a scene. I tried to keep it as vague as possible but the story writes itself, so... Anyway, I did add an OC(please don't hate me). Sorry this chapter took a while, I like to take my time when writing 'romance' scenes. Oh, before I forget. Everything with the OC is very much intended. :P Future chapters may also be slow on coming out because I'm studying for tests right now, so bare with me. I promise there will be more. :)