Me and a friend were taming an Indominus, once we did, we brought it back to base and we thought for a moment!

The Indom Duo fits really well in ARK! Like hybrids cloned to test survivors!
"Test your Might!" taken to a whole other level!

So here is my theoretical lore!

The Indominus Rex was cloned for certain ARKs as a final test for survivors before the last ascension to Earth, it's many abilities were made using controlled Element, like it's camouflage and Roaring Abilities, it's immense power was so unforeseen, that it literally became it's own "force-a-nature"!

It's sub-species, the Indoraptor, was gained by increasing the Utahraptor DNA (if you didn't know, ARK's raptors are Utahraptor, not Velociraptor), it lost many abilities, but it became faster and agile!
It's a powerful thief, and it's deadly, not only that, but it appears to hunt almost everywhere! Beaches seem to be safe! (for now at least)

The Indominus Rex was originally ideas for a failed park, 700+ years ago, it was meant to be a "reboot" of some kind to an older park of the same brand
The ideas for the creature was scrapped, and plans were left in a facility on an island known as "Site B"
The plans were adapted for the creature, using the same DNA, and eventually created it's sub-species!

Very few have managed to see an Indoraptor and survive, and even fewer have tamed them, the Indominus Rex on the other hand? There has been only one to have ever tamed one, and only one to have survived an encounter!