A/n: MM&N don't have an established label for their relationship here. You can view them as brothers, best friends or in a ship/ships. All that matters is they love each other in a weird little magic found family way.
The knowledge Mikami was up to something involving shrines and possibly magic had you uneasy. And after talking with L, you'd both decided that now would be the best time to immortalise the successors before things got even more dangerous. Thanks to Eros, Psyche and Aphrodite you had a solid theory on how to do just that. Even if it didn't work it was worth a shot, and some ambrosia wouldn't hurt them anyway. But first, you had to make sure that this was something they all wanted to do. Even if you and L wanted them with you forever, it was their choice in the end.
Sitting around the meeting table, this time the topic wasn't Kira. The boys and Near weren't sure why you both looked so serious if it wasn't about Kira, but they'd soon find out.
"So... after some asking around and stringing together some theories, we have a way to immortalise you three. If you choose to take that opportunity" L began.
Immediately they perked up, but L was quick to continue before they could jump to any conclusions.
"It'd involve stripping you if your human essence and replacing it with ambrosia, which would keep your bodies alive as long as you aren't deathly injured. Sicknesses would heal, no change of old age or heart attacks. There's a slim change you could still die if you say, got stabbed. But as long as you stayed safe, that shouldn't happen. I won't sugarcoat it, the process will likely hurt, we'd have to strip your human essence with harming spells. You'd feel weak, sick and sore for a while while the ambrosia kicked in. And since this hasn't really been done before, we don't know the effects it'd have on any changes to your physical bodies" L explained.
It was definitely an experimental procedure, but if it worked then they'd be able to live alongside you and L forever. And even if they didn't become immortalised, the ambrosia would heal their weakness from the harming spells anyway. The only risk was unknown side effects from humans consuming such high doses of pure ambrosia.
"I'll do it! I just want to be with everyone forever. And not die and loose all memory of this life as I'm reborn" Mello replied, excitement in his tone.
"Question..." Near spoke up.
You nodded, turning to them to allow them room to speak.
"Theoretically, if you're right about the ambrosia changing parts of our bodies and souls to keep us alive... wouldn't take make us almost Nymph like creatures? Elongated lives with few weaknesses but not quite a deity? All that's missing is the living in a lake part" Near pondered.
"Actually, you're kinds of right. I guess the closest thing to what you guys may become would be a Nymph. I mean, if you really wanted to lean into it I'm sure the kami will give you a lake to dwell in" you replied, a slight snicker at the end.
"You definitely look like a snow Nymph already Near" Mello added, nudging Nears arm.
Noticing Matt had been silent this whole time, you turned your attention to him. He was the only one you hadn't had a one on one conversation about this with yet. He knew you and L were trying to find ways to immortalise him and the others and that they'd leave the choice to the three of them. But he was yet to be askers directly.
"What about you Matt? You don't have to if you don't want to" you said.
"I... don't know. I've always had the live fast die young mindset. But now..." he replied.
"Matt I swear to the kami you aren't leaving us" Mello said.
L held his breath, hoping Matt would join them. He'd respect the decision no matter what, but he couldn't leave one of his babies behind...
"I love you guys, I've just never even considered this before. I mean I always thought I'd just die one day and L and (y/n) could be like my spirit guides in the next life or something. I don't know what I'd do with an immortal life" Matt said.
"Hang with us, solve crimes, play every video game ever. Come on Matt you can't say no, you're one of us. You and the others are the only family I've ever had..." Mello replied.
"I'd respect any decision you made but... it wouldn't be the same without you" Near added.
Matt cracked a slight smile, glad to know the two he grew up under L with saw him as family. As part of the trio and forever connected.
"I couldn't leave you guys, you know that. I guess I'm just self aware I'll probably have an existential crisis at some point knowing life will just keep on going for us" Matt snickered.
"Oh don't worry, you get over that phase after a while. I was a bit of a wreck for a few months there when that happened..." L said.
"Oh I remember that. You could barely get out of bed. I had a moment like that too when I lived down on aether. I think all immortals go through that before they figure things out and find their true meaning in the immortal life" you added.
Mello and Near gave Matt pleading looks, not wanting to loose him to old age or sickness one day. Sometimes you and L wondered what the relationship with those three was, L never raised them specifically as brothers, friends or rivals for the L title. He knew they worked well together and played into that to raise them. Weather or not they saw each other as siblings, just best friends or even a more romantic sense you didn't know. In fact, they probably didn't know themselves either. All they knew was the loved each other, and couldn't loose each other.
"Yeah, I'll do it. I can't leave you guys even if I wanted too, I'd end up back with you at some point anyway" Matt agreed.
L softly sighed in relief, Mello and Near cheering in joy and pulling their gamer loved one into a tight group hug. It was officially decided, the successors would become immortalised and stay at the side of you and L forever. They could stay in the human realm or come live up in the highlands with you and L, whatever they pleased. But first, they needed to drink that ambrosia tea. And it was best done before Mikami realised the death note was gone, and made his next move.