Someone mentioned Earthscorpion's GoD "Witness to Darkness". I believe it's this:
The bold part is what is different from canon WtD. Do remember that an internal penalty remove dices from the dice pool before rolling, differently from an external penalty which removes successes after the dice pool is rolled. Most side-effects from Charms like WtD can be mitigated with Stunts, Excellencies, Willpower or more simply carefully choosing your words. Sure at, for example, Essence 5 the internal penalty is -5, but by that point you can afford to be honest to most people because they lack an high enough MDV to resist you even with the penalty, while with those who could resist it's just easier to be a crafty bastard all the time. But I am willing to use Earthscorpion's version in this quest.
That aside, I am still willing to allow the homebrew Charm "Glaring Sun's Subtlety", if you are okay with losing the potential benefits from both from higher Essence ratings and staying with a simple, fixed benefit for a general cost of 18 Xp, because your aim are the Charms with WtD at prerequisite.
That aside, there are consequences. Infernals are about transhumanism: most time is subtle, like Cecelyne's Transcendent Desert Creature or Kimbery's Spiteful Sea Tincture, but the changes are there.
In the case of Lelouch, it's the eyes. I allowed Dual Gaze Paradox because the advantage from What Is and What Should Never Be is simply a pool of extra stunt dices that cannot, in any case, bring a stunt rating above 3. Even if there is no Stunt, 3 is still the limit. You still have to deal with people becoming obsessed with you.
That aside, if, hypothetically, you purchase both "Witness to Darkness", "Glaring Sun's Subtlety" and "Dual Gaze Paradox", expect Lelouch's sclera to become pitch black, with the pupil being a kaleidoscope of impossible colors surrounded by a ring of burning green. All the time. You will either need to wear a mask, sunglasses or contacts made from Cecelyne's sand to hide that.