Aster stared at the two, forced to kneel before him, and began to think. From the notes from his mother, he knew about the "ancient contract" that bound the two, and how they couldn't refuse commands under its power.
Of course, there are limits to it, but as long as he doesn't overuse the commands, the twins would be unable to touch him at all.
However, the situation 2,500 years ago, when they just formed the contract, the Frostfire Legacy's seal, and right now was completely different. Aster was just too fragile and faced with deadly threats all the time, making the two worried about their survival.
After all—although spirits don't have the concept of lifespan—if their contractor dies, then they would also disappear.
In short, everything stemmed from the fact that Aster was weak!
He closed his eyes, thinking deeply, before taking a deep breath.
"I want you to answer my question honestly." He spoke in a dignified tone, like a lord talking to his subject. "What is your purpose for taking over my body? Is it just to survive longer?"
"Let me answer your question, Master.❄"
"Sister!????"
Seeing that Crysta volunteered immediately, and showing absolutely no signs of deceiving him, Aster let her speak.
"In truth, other than protecting Master by controlling your body and wielding our powers more freely, we also have one more agenda," she explained in one breath. "And that is to release ourselves from the ancient contract.❄"
Spirits gain more power the longer they live.
The two, Crysta and Pyra, originally were low-rank spirits with no form when they just became Aster's contracted spirits. After receiving a name from the contract, they got more powerful. And then, after living for 2,500 years along with Aster, they reached the pinnacle, becoming Queen-level spirits.
As such, although they're thankful for Aster's help in making them reach Queen level (he wasn't aware of it), they figured out that sticking with him would only waste their newfound strengths.
Thus, they decided to start a "rebellion" and try to take control of Aster's body, and further down the road, release themselves from the contract before Aster's life comes to its fated end.
The passives based on the legacy or its minor usage like extracting cores from slimes, thankfully, don't expend his lifespan. After all, the latent mana present in the air could suffice to activate them.
"In short, I need to be careful when using it from now on..." Aster sighed.
He thought he just unlocked a powerful cheat but learned that it was a poison that reduced his remaining years! "As expected, life is not so easy!"
After a while of gathering his thoughts, he decided to shelve the issue for now and asked the two.
"Anyway, now, I've done my part. It's you two's turn now. I want you two to swear under the ancient contract, to never work with the intent of causing me harm, and cooperate with me to the best of your abilities!"
Although he already swore under the contract's name, the two didn't. In short, there's no power to enforce their actions, making it possible for them to betray him at his most vulnerable moment.
Crysta telling him about the price for overusing the legacy directly affected his promise, after all. If either of them overused their powers, using up his remaining life, then he's doomed!
'If she didn't tell me this, then I'd have left a large loophole that they could take advantage of as soon as I leave this place!'
Aster stared at the cool beauty, but he couldn't read what she was thinking under her icy expression. Instead, her next words caught him off-guard.
"I swear under the ancient contract, that I would support Master Aster Mistral in times he needed my power. I swear to never betray him, and follow his commands without complaint. If I ever break this promise, then let the ancient contract destroy my very essence!❄"
"S-Sister...! That's too much! What are you thinking?!????"
Of course, Pyra was confused as to her sister's words. Even Aster was surprised! Placing her very own existence in jeopardy was a bit overdoing it!
The icy beauty shook her head gently, explaining. "To earn Master's trust after all we've done, this much should be natural.❄"
They tried to take advantage of Aster's not knowing how to properly use the Frostfire Legacy, and instead of explaining it to him, they plotted to take over his body! Anyone who has undergone such treatment would indeed have a hard time trusting the perpetrators.
But there's one part that Aster hasn't learned yet—that he can directly use the contract to "delete" the spirits at his whim!
Earning his trust before telling him about such a function would be in their best interest.