Ok, so. There's this spell that is meant to heal injuries attained in war. I learned it from the medic in one of my first battles. Apparently not many humans inquired about spellcasting, and he was proud of making this one up himself so he eagerly explained the inner workings of the spell to me: In sacrificial magic, there are no rules or constraints as to what must be sacrificed to power the spell, contrary to popular belief it's not just blood or a life that must be used. Anyway, he figured that if he could get a soldier to hold the catalyst while he did the casting, he could bind the soldier to a sacrifice: in exchange for the energy on the battlefield (fear, anger, pain, from not just the subject but those around them), the soldier could return part of thier body to the condition it was when they casted the spell. And it worked. He would bind as many soldiers as he could before they entered the fight, and they would emerge from battle with an easy treatment for their wounds.

I saw lots of potential in this, and asked him to write down the spell for me. After the war, I continued my studies in spell modification, and was able to work what was meant to be a convenience into something far greater. The sacrifice of the energy gained from a brief battle was not enough for what I wanted. I searched what little texts I could find on sacrifice magic for any ounces of power I could pile onto the spell without causing detriment: the heat of breath, anxiety, disgust, whatever I could find. In the end, it came down to a simple problem: I had piled on enough sacrifices to power the spell, but gathering this power would take time, and the spell catalysts I had access to were.. leaky vessels. I needed a catalyst that could hold the energy long for the time required to gather enough for the spell. So I searched.

And about a year before I met you, I was looking in the tomb of some great warrior from long ago, and next to his coffin in the heart of a forest I found not one, but two catalysts that had been left for his journey in the afterlife. I was excited, but I knew better than to simply steal them. I set up a summoning circle in the dust of the tomb floor, and prayed hours in the dark to commune with his spirit. And with enough patience his confused ghost briefly took form. "Are you still using those?" I asked him, pointing to the catalysts "Why of course not" he said, "My gifts have served their purpose, and my journey ended long ago." "So I can just go ahead and nab these off you?" "I don't see why not" he responded. I thanked him and sent him back, leaving the tomb with the power of immortality.

"Wait" said my wife "why did you take both of them?"

"I'm getting to that"

Anyway, with two powerful catalysts, I could go further with my plan then I had previously thought. The spell was finished, and I bound myself to a sacrifice: I would surrender some of my anger, disgust, urine and about a paragraph of all the other random things I could tack on to this spell, and in exchange, when it was ready and when I was willing, I could return my entire body to the state it was when I casted the spell.

"So you age a few seconds at a time, and bind yourself back to the spell as soon as you can?" Said my wife "That doesn't really count as immortality"

"No, that wouldn't but here's where the second catalyst comes in"

With two catalysts, I could cast the spell twice at the same time, and when I used one of the sacrifices, the other one would still be gathering power, and I worked it out so that I could re-bind myself to the casting time of the first spell, with the second catalyst. I can never permanently age or get injured. At all.

"But what if you die?" My wife asked "wouldn't that kill you just like the next guy?"

"Not really" I said

I would be dead, but different to most corpses, a spark of hope remains within me. The emotions that one undergoes in their last moments are more than enough to power the spell, sometimes twice over. So it's impossible for me to die without at least one charged catalyst. If somebody can find me, and grip the catalyst in my corpses fingers, then carry out the second half of the spell, I will be returned to my condition at the time of casting.

"Which is alive" my wife realized.

"Exactly"

"And why, exactly, are you only telling me this now? I could have found you dead, and I would've thought I lost you for good. Who, exactly, did you expect to revive you??? I can't believe you would just leave me in the dark about all this. Why didn't you tell me you were immortal on the day we met??"

"First of all, chill, I made an arrangement with the spirit of that guy who's catalysts I took to whisper instructions into the ears of those near my body. Secondly, I can't exactly going around telling everyone I have the secret to immortality, because they will want me to make them immortal."

"Why don't you want me to be immortal?" She said hysterically "I'm your wife!"

"Well I've only got just the two catalysts and.. Actually I could just bind you the same way the medic bound the soldiers. Or I could just teach you the spell. We could share the catalysts and that wouldn't really make a difference. That's a pretty good point you made"

My wife stared at me, dumbfounded.