The Mark of Eternal Love
Albus Percival Wulfric Brian Dumbledore is a great wealth of information. His wisdom can be applied almost universally from scenario to scenario throughout the Harry Potter series.
Today on Twitter, J.K. Rowling explained the changing of one’s Patronus. The answer is eternal love: Only something as strong as eternal love can leave a lasting mark on a person, such as affecting the form of their Patronus.
He didn’t realize that love as powerful as your mother’s leaves its own mark. Not a scar, no visible sign… to have been loved so deeply, even though the person who loved us is gone, will give us some protection forever.” – Sorcerer’s Stone (p. 299)
Now, while the case is different here with Harry being on the receiving end of the eternal love, could it really not apply to the one who loves so deeply? To feel such a powerful emotion as love should also grant the lover with protection. Dumbledore also lends us this thought:
You think the dead we have loved ever truly leave us? You think that we don’t recall them more clearly than ever in times of great trouble?” – Prisoner of Azkaban (p. 427)
The people who love us and those whom we love leave an eternal mark on us.
After all this time?