Marked.

Tattoos are normal. Everyone has them. Everyone is, in fact, born with two.
One, a sign of love. Platonic or romantic. A symbol shared with your soulmate. The other, a sign of hatred; of boiling blood and balled fists. A symbol shared with your enemy - shared with the person destined to cause you more pain than anyone else to walk the planet.
No one alive knows how to differentiate between the two until it's too late - until the pain has been caused by their enemy and they realise they could do nothing to prevent it.
Everyone looks down at their tattoos and sees a confused mess of questions. When Charlotte looks down to her tattoos, she sees no questions, she sees no confusion. They are the same tattoo. She knows that somehow the person she must love must cause her immeasurable pain