Moon has four siblings : Sun , Lunar , Earth and Solar

Solar had died due to Ruin ( a amalgamation of Sun and Moon from another dimension ) destroying multiple dimensions to kill the Creator Council ( The Creator is Sun's , Moon's and Earth's Creator , in their current dimension he's a giant floating brain that's between life and death ) and in the process Solar had died since he is from a dimension where a Creator was still alive

Moon has been loosing his sanity ever since then and since he talked to his Old Self ( his Old Self died to save Kill Code , a code programmed into Moon to kill people but he reformed and gained sentience and when Old Moon died he stays in current Moon's mindscape unable to move unless someone goes into the part of Moon's mind where he's at - Monty , a animatronic gator friend of Moon's is planning to bring Old Moon back )

Moon believes the way to bring Solar back is killing BloodMoon and swapping his dimensional code with Solar's to bring him back

but Eclipse ( a animatronic that was once apart of Moon and Kill Code that Old Moon left in Sun then grew sentiences , died and Ruin remade this Eclipse but he's just a copy with the memories of the original Eclipse ) is planning on bringing Solar back the correct way

Moon doesn't buy it

Moon will do anything to get Solar back , even if it means his own family gets killed in the process

he doesn't care anymore ...

he's gone completely mad and beyond redemption ...

Moon's appearance has a Moon shaped faced ( his colour scheme is dark blue and grey ) , he wears a blue nightcap with gold star print and a bell on the cap , blue colour jester pants with gold star print , brown colour slippers , red colour ribbon bracelets with bells on each of his wrist

he's a animatronic

he was stopped by Puppet who sent him to space

Dark Sun ( another dimension Sun who's evil ) found him , removed the Old Moon chip from his head and they're now working together

Moon changed his named to Nexus ( he hates the name Moon )

and moved in with Dark Sun in his own dimension ( which he technically helped make by building Dark Sun a Dark Matter Generator to make the dimension )

Nexus has workers without AI working for him that he controls with a console

Dark Sun has a Baby Wither Storm that Nexus can study only when Dark Sun is around

Nexus is a completely different being then he once was , he doesn't care about his old family and original life anymore

Nexus wants to test stuff out with Negative Star Power ( the opposite of Positive Star Power ) , needs Wither Shards ( which are parts of a Wither Storm ) , kidnap Sun and kill everyone who gets in his way

hates Moon and completely tortured him

the Negative Star Power is slowly killing him but he has powers now like levitating , mind control , mind reading and zapping people until they're unconscious or dead

Ruin works for him as a servant basically ( though Ruin secretly is only there as a spy )

Nexus wants to use Sun or kill him , he also wants to kill Moon , Solar , Earth and Lunar

he wants to rule over the universes ( possibly )

( in the show he died via Sun hitting him with a fireball attack from his magic but it was a propane tank Ruin got and put in Nexus that really ampt it up - no one knows about this though - you can roleplay his death like this or have your own way )