What I think the Blackrock Stronghold trio would look like as kids.
There are some pretty good (in my opinion) explanations behind the designs:

Rythian

I wanted Rythian to look a bit like he does as an adult, but I also wanted to add the more childish feeling to it, hence the messy hair and playful curiosity.
I then began thinking of what could substitute his mask/cloak. I thought he was simply too young to have one, it wouldn't make much sense. I thought about keeping his face bare but since I fallow my headcanons by heart (Hence some of my tumblr tags concerning the Yogscast fanart say "Eps'AU") I decided to not do that. Instead I remembered a character I love that reminded me a bit of Rythian.
Dororo from Sargent Frog/Keroro Gunso whom hides his face for reasons no one really ever explained. Behind that mask lays a mystery and that matches well with Rythian. Now how did Dororo inspire me? Well simple, as a child he used a medical mask to cover his face, so I did the same for Rythian. And somehow, it just feels right. I's something you feel compelled to look at and try to figure out, but never quite get an answer to why it's there. I deem it perfect!

Zoeya

To me, Zoeya's whole existence is quite fascinating. She fell from the sky and rambles on about mushrooms. She can understand them as well and names inanimate objects.
It's also rumored she might be part blaze.
Every time I try to write from Zoeya's perspective, I get a mindfuck because she's just so unique in her own way that I can't quite even attempt to copy her personality into my writing.
Unlike the speculation of Rythian's origins, I came to notice that there are only a few ideas of where she came from.
It grinds my gears that I have no idea where she might have come from, so I imagine her to be very simple and cheery as a little girl. No fancy clothing or real stylish sense (leave that to her teen and adult self) because she's happy with just being herself.
Where ever Zoeya comes from, I hope we'll get to find out, on the meantime just have this as a design I figured she'd have.

Teep

Teep was the easiest to design. I imagine him running about cheerfully, bottom part of the eggshell still sticking to him like a diaper.
He was either raised by other unknown dinos (who might have died off due to some strange happening) or he might have been adopted by some humans or even some birds of pray. No one really knows. Like Zoeya, Teep is full of mysteries, specially concerning his origins.


Hope you like the designs, I'll work on more soon (Sorry these don't include Sips and Sjin, I'm kind of having issues with their designs) and hopefully the next Tekkit Rebirth won't make my feels explode like a volcano.