Lucy groaned as she dragged herself up the stairs to her apartment. How did they do it? How did those three manage to stay so energetic all the damn time? It was inhuman! It was monstrous! It was stamina on a ridiculous level and they expected her to keep up! She fiddled with her keys for a bit, getting the right one and opening the door, fully expecting to take a long, relaxing bath and then sleep until morning. She didn't want to see a single other person until she woke up tomorrow.
"Yo, Lucy!"
"Hey, Loki."
She blinked.
"Loki! Wha- Why the hell are you in my apartment? Where's Natsu?"
Loki looked confused. "Natsu? Why would Natsu be-"
"I don't know how! He just shows up! Like you have!"
A flirting smile spread across Loki's face. "Why, my dear, might I have to fear your affections being stolen away by that fire-eating brute?"
Lucy sighed and rested her face in the palm of her hand. "Loki, please, either tell me why you're here or go away, I'm not in the mood for your flirting right now."
Loki, suddenly serious, leaned back in her armchair that he was using. "I'm here, my blonde beauty, because of a problem you have that has recently become pronounced enough for us, that is, the Spirits you hold a contract with, to be concerned."
"Wha..?"
"Lucy, you're an idiot."
Fatigue was forgotten instantly. "What's that supposed to mean?"
Loki scratched his head. "Lucy, let me ask you a question. Would you say Karen was a powerful Celestial Spirit Mage when she was alive?"
"Wh... I don't know. I mean, she was pretty famous, so I guess she must have been..."
"What about Angel?"
"Definitely."
"I see." Loki took a deep breath before looking her square in the eyes, "Lucy, Karen couldn't summon more than one Spirit at a time. That's why my refusal to leave the human world posed a problem for her. She just didn't have enough magical power to maintain the presence of two spirits at once. She also couldn't force closed summon gates, which is an incredibly rare ability anyway.
"Do you even understand just how much raw magical power is required to summon more than one Spirit at once? Do you know how many Celestial Spirit Mages in recent memory could? How many in history have been able to? Now, how many of those wizards do you think were able to force closed their summon gates?
"You said that Angel was a powerful Celestial Mage, but in your battle with her, did you not notice that despite possessing three Golden Zodiac Keys, she only ever had one of those spirits active at once? Certainly, she used Caelum in conjunction with them a couple of times, but never two Gold Keys at once. You had more power than she did, but she knew what she was doing better than you did."
"W-Well... that's..."
"I'm not finished. While we're on the subject, I haven't mentioned the number of Golden Keys in your possession. Most Celestial Spirit Mages have only ever had one or two, or maybe even four, if they were lucky or resourceful enough. You currently have nine. There have only ever been a handful of Mages throughout history to hold more than six keys at once, and only one or two ever obtained all twelve. This, coupled with your great magical reserves and ability to force closed summon gates, makes you, in terms of raw power, almost certainly the most powerful Celestial Spirit Mage alive, and quite possibly one of the most powerful in history.
"Yet, despite that, you still almost lost to Angel, who by all rights should be weaker than you, and if Hibiki hadn't been there, you would have lost outright. You would also have died – and don't object. Even if Gemini couldn't bring themselves to deal the finishing blow, Angel would have been perfectly willing to drown you herself right there."
Lucy had gone quiet, digesting everything he said, while trying not to listen.
"That's why we're concerned, Lucy. You are one of the kindest mortals we've ever contracted with, as well as one of the most powerful, and yet you show no regard for strategy or tactics when you call us. You send out Taurus or Aquarius or even me whenever you can simply because, in your mind, we're the most powerful Spirits you can call upon. Lucy, you can summon more than one of us at once! We could work together in battle. We could combine our strengths with teamwork. We could be commanded far more efficiently if you just put a little thought into what you're doing!"
Lucy had long ago flopped down onto the side of her bed. She had heard everything he said. Even listened to it, as much as she didn't want to. It... hurt. It hurt being torn into like this by someone she considered a friend.
"That's why, Lucy, I'm telling you this. You're an idiot, and you need to stop being an idiot. None of us want to see you die. Not even Aquarius."
He sighed as stood up from the armchair he'd commandeered. "Well, this is probably a lot to take in at once. I'll let you sleep on it. Just know that if you want to improve on this, we'll all be behind you. Good night..." He disappeared in his usual manner, leaving Lucy with her thoughts stewing over.