I agree, I suppose this is true love.
But what I meant to say: there is no evidence in the books that for example Michael and Charity are protected. I mean they are already under protection of the angels.
Did Thomas ever go into their house? I can't remember. Did Thomas ever touch either of them? Maybe I'll put special emphasis on looking for those moments during my next reread.
Thomas wouldn't prove anything either way. Neither would Lara. Madeline would, if she wasn't dead.
Remember what Thomas explained to Harry about how that works back in
Turn Coat: the Hunger demon
tries to feed every time there's flesh-to-flesh physical contact between a White Vampire and another human being (including another White Vampire!). But most WVs, most of the time, can restrain the Hunger so the attempt is stopped. Thomas' Hunger tries to feed a little from Harry every time they do that knuckle-bump move, for ex. But it's easy for Thomas to restrain the effect there.
I said Madeline would prove something touching Michael/Charity because as Thomas noted, she had so little self-discipline that she could never restrain her Hunger, she let it try to feed every time she touched someone, so she always triggered any Protection she encountered. But Madeline is suffering from a case of terminal death.
The burn effect kicks in when the Hunger actually begins to feed. Thomas gets burned by Justine because his Hunger wants to eat her so bad he can't restrain it with her. But he could touch Charity or Michael and it would be fine unless for some demented reason he tried to feed, then I'm pretty sure zap. (Even assuming the angels let things go that far.) Lara, likewise, could shake hands with Michael or Protected Harry and be fine as long as her Hunger was on the leash.
Remember
White Night. Harry and Lara were actualy making out, so Harry could use the emotional energy to drive a spell. This had gone on for a couple of minutes, but she only got burned when her Hunger slipped the leash for a moment, then Susan's energy burned Lara's mouth.
It's the
energy that burns the WV when they try to
feed on it, if it's been 'tainted'.
That's why sex (or according to JB, other theoretical ways) is necessary for the protection. John and Jane might love each other with the deepest of devotion, fully prepared to die for the other if need be, but if there's never been sufficient physical contact to transfer the 'tainted' energy, they aren't protected because that taint isn't there.
It's not about 'fair'.