Douglas had been hesitating over whether to acknowledge Harry as family.
He carefully recalled Dumbledore's actions over the past year.
Putting all the details together, he found that Dumbledore seemed to want him to protect Harry.
Especially after he had put out that piece about the Half-Blood Prince, along with the matter of Harry being a Parseltongue speaker.
Whenever he intervened in anything involving Harry, Dumbledore seemed to let things take their course, showing no intention of grooming Harry and instead leaving Douglas to make the decisions himself.
Even then, he had been deliberately fostering a relationship between Douglas and Harry.
Douglas did not particularly object to protecting Harry. After all, as a professor, he naturally had a responsibility to keep his students safe...
No. Douglas suddenly realized that he seemed to be overthinking things. Dumbledore had not yet found the Resurrection Stone, there was no sign of Voldemort returning, and Sirius had not yet cleared his name.
So, if things followed their normal course, Harry would have to die to destroy Voldemort's Horcruxes completely.
He was making up for it, making up for the family affection Harry lacked...
But that did not make sense either. According to the plan Douglas remembered, Dumbledore was supposed to groom Harry to the point where he could shoulder his responsibilities and face death calmly.
But if Douglas became involved now, even if Harry could face death calmly, had Dumbledore not considered whether Douglas would agree?
Possession!
A word flashed through Douglas's mind when he saw his own book on the shelf.
He suddenly realized that no one had ever seen what would happen when a soul attached itself to another living person. But according to some circulating research into Dark Magic, when a soul attached itself to another person, it could replace them.