Ok, so what happened was I got the immortality quest. I summoned my councillors to make me immortal, and because I had high learning I could ask my court chaplain to study about immortality. A few months later my court chaplain is sleeping on the job so I hire him more scribes. A few months after that, he introduces me to a woman who's supposed to be some kind of mystic. Turns out this woman is a little 10 year old girl (also a lesbian). I say cool and have her on board (grabbed a heresy malus for that).
My councilors came in and said she's a fraud so I let them investigate her. A few months after that they said she's cool. Next event, Kumara the 10-year old lesbian genius mystic takes me for a walk and we meet a drunk man begging on the street. She tells me he wasted all his money away because of poor decisions. I get a few choices, but I decided to take compassion and give him 6 gold. Kumara approves. Next event, she tells me I need to go into the forest and meditate and fast without food until I reach enlightenment. My character says he'll die of starvation if this continues, but I choose the option to continue fasting and I succeed, getting the shrewd trait and Kumara's continued approval. The last event after that, she gives me a herbal brew and says that I must drink it and my soul will leave my body. I must then navigate back into my body to achieve what I search for.
So I go for it, and that's the result.
According to the forums, this is actually a really hard event to clear as not only is there a 80% chance that your mystic is a fraud, but every single one of the events has a high chance for failure too. This is also the same guy that lost an eye to cancer, beat pneumonia, and beat dysentery.
This kind of immortality is also a "super immortality".
The way immortality in CK2 works is your character's age is effectively "frozen" from the moment you're immortal - your portrait doesn't change due to age. They retain benefits of Attractive if they become immortal young. They will never become infirm or incapable due to age. I need confirmation but I don't believe women over 45 can have children even if immortal. Disease, injury, and age cannot kill you, but anything that would outright kill you immediately (like execution, assassination, holmgang, duel, combat) will kill you.
This ironman nomad game is going to be bonkers.