Jane briefly went over his current situation.
'I was fighting this woman, and winning, before she used that weird spell on me and I died. The moral of the story is... It's fine to use magic inside of people as long as you do it quickly enough.'
The fact that he even got that far against a clearly superior opponent was already enough for him. He had no real plans of winning, anyways.
'I wonder if they got away safely? Teacher might be bawling his eyes out already, but I already explained the situation to my brother, so... Oh, I have to sort out my body first.'
There was an unusual sensation whenever he looked down at his unfamiliar body. It was like... grief? Longing? He had never felt something like it before, so he chalked it up to Vanessa's experience.
'Right, this woman's name is Vanessa. Uhh, why was she after me again? Let's see. She was ordered to by the bishop... Get out... shoot.'
He frowned a little. Well, it might not have looked that way, with how mangled his face was. Looking too deep into that woman's memories was risky, since her ego could begin flaring up at any time. Jane managed to stay in control precisely because he prepared for this situation beforehand.
'It worked, didn't it. My plan.'
In the weeks leading up to his death, he had thought seriously about his situation. Even if he was immortal, there was no guarantee that he would be able to take control of whatever body he ended up in. Therefore, he laid a trap.
In nearly every waking moment of his, he repeated words that would bring his ego to the surface. Things like 'My name is Jane' or 'Who's body is this' were things that he would say only if his mind was intact— therefore, the target would convince themselves to put Jane in control.
'We're in the same boat now. Since we were attacked immediately, that means you no longer have any allies... Shut up... Hey, I didn't want to cut myself up either.'
Indeed, taking any actions which acknowledged the existence of another entity would inevitably give them power. It would be too risky to forcefully make use of the original's memories, so he needed to cooperate to some degree.
'We just want that, right? But you'll flare up... Concealed... Right, so you don't care about being... Tolerate a bit... It'll take a moment, so don't fight back.'
The mirror in the room was broken, but the remaining shards still reflected enough of his appearance. Making use of Vanessa's muscle memory, he formed an eerily sharp blade of ice.
'Oh, so it reduces inflammation and... Treat me right...'
Jane undressed in front of the mirror, and threw the bloodstained rags aside. His entire body was covered in lacerations and bruises from the earlier struggle. It seemed his work was cut out for him.
'You fucking... What else am I supposed to do?'
Luckily, all of the cuts were located in places he could see. He started with one on his leg. He had never attempted healing without leaving deformities, so he wanted to practice before attempting the face.
The cut wasn't especially bloody or painful, but he could tell it was deep. He needed to know exactly how deep, though. So, he put his fingers on the two edges of the wound, and opened it up completely.
'...Use light... Ah.'
Jane closed the wound again, then cast a few 'Light' runes inside a circle. The powerful illumination let him see through his flesh. In particular, there was a clear line of where he had been wounded. Jane made sure to enclose only that area inside of an 'Include', then used 'Grow' on it.
The wound quickly stopped hurting, but a line of scar tissue grew on top of the seam. Jane had already foreseen this, so he carefully cut the scar tissue out before holding the two sides together and healing them again. It still scarred a little, so he repeated the process until the traces were completely gone.
'What a pain... Whose fault...'
Jane got to work on the rest of the wounds, laboring for hours and hours before he was done. He made sure to use his mana as efficiently as possible, since delays might aggravate Vanessa's ego further. It was already night by the time Jane's skin was smooth and unblemished.
'You might want to look away for this... Who do you think I...'
Despite her claim, Jane could clearly feel a sense of revulsion when he looked in the mirror. Hatred and desperation erupted from an unfamiliar part of his mind, staining his thought process.
'You'll go away after... Sometimes...'
Jane sighed, causing a little bit of air to whistle through his "nose". Actually, barely any of Vanessa's face was intelligible. What used to be a nose had collapsed completely, leaving barely any room for the nostrils to work. Her lips had more or less disappeared, and so the dizzying pattern of her broken teeth was on full display. While her eyes were pretty much fine, the skull which used to accentuate them had a dent in it, and traces of cracks all around.
'I'll look for a bit... Okay...'
Jane decided to start with the nose. Again, he harvested bones, skin, and flesh, then used them to modify the nose into a recognizable shape. Then, using the image from his memory, he cut parts out and substituted as needed. The sight of his perfect nose on top of such a damaged face made him want to laugh, but Vanessa might never forgive him if he did.
When it came to the skull, he cut out the pieces of bone that were malformed, and used fragments to patch up other areas. While ignoring the tears flowing from his eyes, he rearranged and repaired the teeth into neat sets before healing them. He made small adjustments to the overall structure, then stepped back and looked over his work.
There was now a breathtaking young woman standing in front of the broken mirror, with delicate red lips and a petite nose which drew attention to her scarlet eyes.
'No wonder why she found us so easily. She modified her eyes into magical tools. Oh, she quieted... Arrogant...'
Jane peeked through a crack in the wooden planks composing the shed. Outside, there was a field of golden wheat swaying in the night. Even up to a hundred merds away, he could clearly see every single bushel of grain as it moved with the slight breeze. He glanced down at his naked body.
'Am I really going to go through the effort of... Yes, you...'
Ignoring the voice in his head, he cleaned the tattered robe and put it on. It didn't cover all of his body properly, but that didn't matter for him.
'We need to run... Escape...'
It was a good thing that Vanessa took the locket from his corpse. He activated it, strengthened his legs, and began running far away. After an hour or so, he thought he could hear an explosion coming from the general direction of the shed. Accordingly, a mushroom cloud of ash grew out of the horizon behind him.