The pup stopped just a few meters into the cave, at the point where the outside light had completely faded.
[Dark... scared.]
[Now you're scared? Can you listen to me and wait.]
Robert moved so that he was in front of the pup. [It's dangerous here.]
[Angry?] the pup asked, tucking its tail in between its legs.
[Yes,] Robert replied, before focusing his attention on his new surroundings.
Luckily for them, there were no glowing eyes at the dark end of the cave, so atleast the beast had not noticed their presence.
The red trail that Robert had seen outside led just a few meters into the pitch black darkness of the cave. 'Gaining another one of those red crystals would be beneficial, however the danger isn't worth it,' he thought, before looking back at the pup.
It was still shivering, with its head pointed away from Robert.
[What? Are you angry with me too now?]
The pup did not respond.
'Kids,' Robert thought to himself, remembering his own little boy.
What a father, to not only kill the world promised to his child, but kill his child as well. He had thought he'd come to terms with all that he had done, but the familiar feeling of having a child had breathed new life into his regrets.
'We have to move deeper into the cave,' he realized. Otherwise the pup would freeze. 'However, I'll need to make sure that it's safe.'
Looking back at the pup one last time, he hesitantly ventured into the darker sections of the cave. The red trail was glowing warmly against the backdrop of darkness, leading him towards the right.
When he finally reached its end, where a cloud of red mist was visible, he braced himself for the worst. Without any light, he was basically a sitting duck. But atleast he had the element of surprise. The creature he was being led to had not moved since he entered, so at the very least it either did not know of his presence or was too weak to do anything about it.
He moved into the red cloud hesitantly, bumping into a small mound.
『Tier 0 Radioactive nucleus has been collected!』
'So the creature is dead.'
『Processing...』
'Yet the question remains. What killed it?'
『1 Rad has been processed.』
『Nucleus traits have been processed.』
『User currently does not have the necessary build tools to view nucleus traits.』
'Good, good. Hopefully I get something as useful as the last time.'
『1 trait is being selected at random...』
'Wait, if it chooses a trait, then that means I'm going to lose consciousness again.'
[Pup, come here!]
Robert got no response.
『Trait: Echo-location has been selected. 』
[Look, I'm sorry for being angry. Now come here. I have food for you,] he pleaded.
『Restructuring DNA to sync with new trait...』
『Processing...』
[Coming... mother,] the pup responded, right as the electric charge exploded in his mind.
Just like before, a vision played in his mind.
In the first scene he was upside down in what looked like a cave. The only source of light was a glowing blue pool below him.
Then he was soaring through the night sky. A green moon, and dozens of mishapen flesh creatures stalking the land below. Fear consumed him. 'Do not land', those words repeated in his mind, relentless in their warning.
The vision shifted to a cave. Two glowing green eyes peered at him from the far end. Pain consumed him and darkness followed.
『Processing...』
『A mutation has been performed based on world data.』
『☼Audio-visual sensing☼ mutation』
『Auditory expressions have been linked to visual expressions.』
『Syncing audio-visual expressions to neuro-logical system.』
And so Robert came to experiece sound for the first time since he had arrived here.
The howling of the winter winds outside the cave. The subtle trickling of water inside the cave. The almost silent crawling of insects deep inside, and the whisper wails of some strange beast even deeper within.
'I think the world was a better place without sound.'
There was some whimpering right beside him, soft and frequent.
[Is that you?]
The whimpering stopped.
[Mother?]
[Ye- no, I'm not your mother. But yes, I've returned.]
The sound of licking followed right after. Robert was incapable of feeling anything besides the cold, so he could not register the licking, however he understood the sentiment.
[Have you eaten?] he asked.
[Yes... some left for mother.]
'It's leaving me food now?'
[I don't need food. As far as I'm concerned, this body does not require nutrients.]
The pup remained silent for a moment.
[Confused...]
'That sentence was too long for it, huh?'
[I do not need food.]
The pup remained silent at that too. Perhaps the very concept of not needing to eat was what confused it.
Robert decided to focus his attention on the new mutation he had undergone. Yes hearing was beneficial, but when the system had mentioned echo-location he had expected to have the same ability as a bat.
'Perhaps it's just like all the senses before? I have to search for it in my mind and try to understand it's default working?'
Robert went into his mind, and searched for any parts that seemed new. After a little while he found it.
It was an area of his mind that flared up every time he heard a sound. Just like when he had initally gained light sensing, it was a series of annoying blinks.
'Hmm, why hasn't the system converted it into a form I can better understand?' he pondered.
The only conclusion he could come to was that it was a sense completely unfamilair to his mind. So even if the system had wanted to, it had nothing to convert it to.
He would just have to use the scientific method to figure out how it works. After all, as a physicist, explaining natural phenomenon in simplest form was his specialty.
First he observed how it functioned. Every sound that he heard, caused a blinking signal in his mind that subsided after a few seconds. The louder the sound, the more frequent and shorter the blinks. The opposite was true for the softer sounds.
'How does this new sense function? Is it at all like the echo-location I'm familiar with?' he asked himself.
He then focused on the way that the different blinking signals behaved, looking for patterns within them.
However even after some more observation he couldn't find anything.
'I need something to compare it too. But the only other blinking signal I know of is from my light sensing mutation,' he realized.
'Is it still available?'
He searched the section of his mind that had to do with vision. He quickly discovered that although the processing had been abstracted for him, the blinking signals were still present.
He kept track of both the visual and auditory signals, trying to find consistent patterns between the two. This was a slow process since the only light that he could see was from outside the cave, and night was quickly falling so even that was quite dim.
Still after only a bit of time, he found a pattern.
The blinking from the visual section of his mind drew images. He was still unable to decipher the complete image without the system abstraction, but a certain sequence of blinking indicated the presence and size of an image.
Linking it back to the new auditory sections, he could decipher the size of an object creating a sound. And so he came to the following hypothesis.
'The echo-location is indeed similar to the one I am familar with.'
In order to confirm it, he would need to run more tests.
[Pup, are you ready to help me with something?] he asked.
The pup made an odd sound, before replying.
[Play time?]