When Dr. Conners did that experiment on Inigo that caused him to be that hybrid were tiger beast, there were probably all sorts of ramifications that Inigo didn't account for when combining his DNA with ANIMAL DNA. While he might not have been the wielder of the amulet though, he was training for it so his body is handling the experiment better than it would for a regular human but Iker kind of helping him try to wrangle control to the tiger DNA side. But imagine Iker seeing and confronting that hybrid animal-beast side of Inigo and because its pure instinct, it recognizes Iker's scent as an apex predator and growls and attacks and while Iker doesn't think even that'd be enough to kill him, he will admit that some of his attacks did hurt a lot more than usual and that he just falls onto his back and whimpers, just to appeal to Inigo's animal brain and letting it know that he submits to him. Which works as the Beast-Hybrid Inigo just purrs softly in satisfaction and climbs on top of Iker, Iker just digging his finger tips into the ground to silence the sound of his claws unsheathing in case it doesn't work but then he suddenly feels Inigo's rough sand paper tounge on his neck as he starts to bite it and he starts to go back to his original form and he's purring. Iker is STILL confused by what the fuck is going on before he shoves off Inigo and stands up and he's all: "WHAT THE HELL DID YOU DO TO YOURSELF!?"
And while having that primal animal side is good, you still need the intelligence and restraint of a human to control it so Iker just kind of helping Inigo control that side of him because he's already a victim to acting out on his own rage and Iker just doesn't really like that side of him because it feels like a mockery of his own perfect apex predator biology (like the best way I can describe Iker's feelings was if a natural wild animal was to meet some wierd man-made artificial animal, the wild animal would experience an uncanny Valley feeling and become instantly defensive because it recognizes that the artificial animal is not truly one of them).
But yeah, Inigo grumbling to Iker that he doesn't need the training and that he's fine. Or he just shoves Iker and tells him that he doesn't need shit from Iker and that just because he was designed to be the "the perfect biological weapon" doesn't mean he gets to tell Inigo what he can or can't do with his own DNA. So whenever Inigo does become that or his artificial DNA activates, Iker lowkey falling back into the shadows during the fight and he just prowls around cautiously because yes, Inigo might be fighting the enemy but Iker is a scientist and wants to observe Inigo's new abilities for himself to be able to make theories and tests, but he also doesn't know how much Inigo is able to hold back because even tigers can kill their own mates for various reasons. At the end if it, Inigo smirking and immediately looking at Iker's hiding spot and he's all: "Aw, Gatito, did I scare you up there?~" and he sees Iker's glowing eyes just staring at him before Iker slowly walks into the shadows and dissapears and Inigo frowns and furrows his brows but shrugs it off.











