here are all mentions of the trials:
“Karkat: Leave your room.”
You step outside your respiteblock, onto one of your hive’s numerous extraterraneal landing slats. You were allowed to design this hive when you were young, after you emerged victorious from your trials deep in the brooding caverns. You have lived here with your CUSTODIAN ever since.
“Karkat: Deal with crabby customer.”
The eggs hatch into young larval trolls which wriggle about to locate a cozy stalactite from which to spin their cocoons. After they pupate, the young troll with his or her newfound limbs undergoes a series of dangerous trials. If they survive, they are chosen by a member of the diverse and terrifying subterranean monster population native to Alternia. This creature becomes the troll’s lusus, and together they surface and choose a location to build a hive. The building process is facilitated by CARPENTER DROIDS left on the planet to cater to the young. But only for building. They’re on their own otherwise.
“======>”
AG: Nothing comes easy, Tavros. That is why we go through the trials in the 8rooding caverns when we are young.
AG: To make sure we are strong when we come out!
AG: Do you remem8er the trials, Tavros?
AT: nOT VERY WELL, nO,
AG: Well, I do, and they were a 8itch.
AG: 8ut now that I think a8out it, it would make perfect sense if your trials were really easy 8y some mistake.
AG: That is why you are such a soggy phlegm sponge, and why you got picked 8y such a sad, frail little lusus!
AT: }:(
AG: 8ut that’s ok, it pro8a8ly wasn’t your fault. Just a 8ad 8r8k!
“Terezi: Examine douthchebag.”
The youngster receives striking new eyewear. Quite a handsome set. Perhaps it is customary for this species after emerging from the trials in the brooding caverns?
Or just MAYBE, this is some sort of coolkid you are dealing with here.
“[o] ==>”
The Sufferer required a less conventional upbringing to reach maturity. As a young grub, he landed in the brooding caverns where he would be expected to face his trials. But due to his mutation, surely no lusus would select him. No creature sympathetic to his scent had been bred yet. His odds for survival would have been remote, if not for a chance encounter.
from all of this, we can gather a few things:
- the trials all take place in the brooding caverns where troll grubs are born. the moment trolls hatch from their cocoons in their new, humanoid bodies, they begin the trials
- the trials are dangerous and not all trolls survive them. it is considered an achievement to make it out of the caverns alive
- it’s unknown what the trials actually are, and we will probably never know! however, we know that they’re deadly but still not deadly enough that toddler eridan was unable to survive them, which is impressive
- the trials are presumably intended to strengthen young trolls and weed out the weak ones. the presence of the trials is likely one of the differences between beforus and alternia
- after surviving the trials, trolls are chosen by lusii and go off to design and build their own homes