Mainframe, a great beast reconstructed into this mechanical abomination. It roams the world of Terraria looking for a vessel.
When the sky turns black it awakes, searching.
Only the greatest warriors attempt to face it, all of which didn't manage to kill it...
One day a Godly adventurer stepped into its domain. It awoke, screeching at the Warrior.
The warrior took out a powerful weapon, which was infused with the souls of another great mechanical beast.
Mainframe noticing the threat level of the warrior attempted to flee but the warrior followed battering Mainframe's Metal infused tissue.
Mainframe tried to fight activated its defense protocols but alas it failed.
Many days later it was Hijacked by an unknown Spirit, all that is known is that it's friendly.
The spirit possessed one of Mainframe's minions and began to roam.
Eventually the spirit found a beheaded adventurer giving it to latch on to the body creating a suitable vessel.
It eventually found a place to settle, however it did not know this was the adventurer's home.
After some explanation the adventurer accepted the Spirit into their town.
It was given the nickname "R.A.N.D.Y" by the townsfolk.
It was happy.