Lusus

The Lusus Naturae, also known as custodians, are the Hivebent equivalent to a Guardian. They look after the young trolls whilst the adults beseige other star systems in the name of Alternian glory. Trolls and their custodians have a peculiar arrangement of codependence. The lusus behaves as a lifelong bodyguard, caretaker, and visceral sort of mentor, while the young troll must learn to function as a sort of zookeeper.

They are horrifying beasts found in the ceremonial brooding caverns once the young trolls have completed their many dangerous trials. Together the young troll and custodian surface from the subterranean vaults and build a new hive using carpenter drones.

It was revealed that all of the trolls Lusus' would die (with the exception of Terezi Pyrope, who doesn't have one), due to the effects of the Mobius Double Reacharound virus, and that all would be prototyped with their respective troll's  Kernelsprite. They were all protoyped before entering the medium so the Troll's enemies have all their characteristics. After prototyping the Custodians gained the ability to talk with their charges for the first time.

It seems likely that the custodians will each correspond to the zodiac symbols of the trolls.

apocalypseArisen's Lusus
Nothing yet is known of AA's lusus.

Tavros's Lusus
Tavros, strangely enough, has a fairy/bull hybrid lusus that's barely any bigger than his head. Affectionately dubbed 'Tinkerbull' by the forums, and later referred to as Tinkerbull by Tavros himself. They seem to have a very good relationship.

Sollux's Lusus
Sollux's Lusus is a massive two-headed, horned giant called a Bicyclops. It has one eye on each head, one red and one blue, fitting with Sollux's red/blue theme, and a barely visible mouth below each eye. It eats mind honey, harvested from Sollux's beehouse mainframes, to "keep it from being an idiot all the time". Sollux chains him to the roof of his communal hive stem, whatever that is.

Karkat's Lusus
Karkat's custodian is a towering, bipedal crab monster with a taste for chilled roe cubes. It was killed when Karkat's computer exploded as a result of running Sollux Captor's Mobius Double Reacharound Virus, thereby implementing the curse that leads to the death of the other troll's lusi as well.

arsenicCatnip's Lusus
Following on from this theory, arsenicCatnip's lusus might be a cat-thing with two mouths.

grimAuxiliatrix's Lusus
grimAuxiliatrix has been shown to have a large, flying bee/moth-like lusus. It has a skull-like face, lips, and two horns, one of them bent like gA's. It is possibly based off of the Grammia virgo, or Virgin Tiger Moth.

Terezi's Lusus
In a marked difference to the rest of the trolls, Terezi has noted that she doesn't have a custodian, at least not yet. In her own words, "1F 1 3V3R D1D H4V3 ON3 1T WOULD M34N TH3 WORLD W4S COM1NG TO 4N 3ND." It is possible that she may acquire one, as the Trolls world is destroyed as part of the game.

arachnidsGrip's Lusus
Nothing yet is known of AG's lusus. It will most likely be archnid like, probably a scorpion.

centaursTesticle's Lusus
Nothing yet is known of CT's lusus.

Gamzee's Lusus
Gamzee's lusus is a giant goat-like sea creature. It had apparently often been out to sea instead of caring for Gamzee as a custodian is supposed to. It is killed, speared by what appears to be a harpoon or something similar.

caligulasAquarium's Lusus
Nothing yet is known of CA's lusus.

cuttlefishCuller's Lusus
Nothing yet is known of CC's lusus, though it can be assumed that it may either be a squid, fitting their name or fish, in reference to their zodiac sign, pisces.