"You cannot corrupt someone who's already corrupted."

Ange has already been voluntarily corrupped in the past, in his futile and desperate attempt to become unconscious of his existence. Alas, his passive ability to make him impossible to be controlled played a terrible joke on him - in short, nothing good came of this venture. But he never was uncorrupted, too.. eventually, he just supress the corruption within himself. So, it's still with him, and still trying to break his will sometimes. Ange resists this perfectly in his normal state, however, if his morale drops too low, then breaking his will will also be easier, and may bring him to this half-corrupted state.

• yet, it can only be unleashed when it's dark;
• this condition can be get down only in sunlight, until next time;
• Ange remain sane despite the state, but become more sinister and aggressive, focuses all his attention on opponents, at most simply ignoring those who do not pose a threat to him or his allies. Will listen to those who are close to him.

And yes, those is not tectacles or spider legs, it's non-flyable wings witch able to function as clawed paws.

Partly inspiration: Takeharu Ishimoto - Transformation