(POV Dumbledore)
This summer holiday had turned out to be quite interesting, to say the least, he had to admit. 'First came Peter's capture and Sirius's release, and now it seems that strange young man has somehow acquired a ho-ho of all things during that same span of time,' Dumbledore thought as he watched the rooster-sized black and red bird chirping happily back and forth with Fawkes inside his office. 'According to Helena Ravenclaw, this immortal bird may in fact be older than Fawkes, since it was gifted to her mother more than a thousand years ago,' he reflected seriously.
Dumbledore remembered Dusk's arrival at the castle very clearly that morning, together with Helena and a house-elf named Dotty. He had been seated at his desk working through the stack of paperwork that had recently piled up before him, ranging from matters involving Sirius's release to reports on the movements of Grindelwald's forces. Fawkes had warned him only moments before Dusk flew into the room through the perpetually open window near the top of the office. Dumbledore was not ashamed to admit that his eyes had widened dramatically and that his jaw had slackened in surprise.
How could he not be startled when he knew perfectly well how solitary each of the immortal bird species tended to be? For one of them to appear so casually out of nowhere for no obvious reason was enough to make even a wizard of his experience blank for a moment. Fawkes, on the other hand, had quickly made his presence known to the newcomer, though he seemed genuinely surprised when the ho-ho reacted with obvious happiness at meeting him. It was only after Helena arrived that Dumbledore understood the reason for this. There was a fact about immortal birds that only those with true knowledge or power tended to know, namely why they stayed with their parents until adulthood.
Immortal birds possessed what were called nirvanic personalities, which, put simply, meant that the way they were raised and shaped during their first lifetime remained with them permanently forever after. Because of that, gifting someone an immortal bird chick was not merely the transfer of an unusual magical creature from one person to another, but a profound act of trust that the recipient would not permanently twist the bird into some powerful evil being. Dusk had very clearly been raised in isolation and with very little affection, as though he were not an intelligent being at all but merely some simple magical beast.
He was not evil, but he had been starved of real companionship and had grown bitter toward the world because of it. As a result, the moment he found companionship, he clung to it fiercely and reacted violently toward outside interference, a fact Dumbledore had learned firsthand. He was now sporting a beard that was slightly shorter than before because of Dusk's warning strike when he had tried to make the bird leave his office while it was communicating with Fawkes. 'Like master, like bird, it seems,' he thought, remembering how strongly Julian had reacted to his own actions as well.
Needless to say, he had quite the headache on his hands, because there was very little he could actually do about a bird like that occupying his office. The worst part, however, was the nightmare of knowing that Dusk apparently went everywhere with Julian, according to Helena. There was honestly no chance that the bird would not cause a major disturbance during classes. Worse still was the need to convince Hagrid to keep his distance from the creature before it decided to disembowel the half-giant after being bothered one too many times. For all the large man's skill with magical creatures, he was rather dense when it came to recognizing when he ought to leave them alone.
None of that, however, truly mattered compared to one single piece of information Helena had let slip by accident. Julian had somehow found a way to allow a ghost to take on corporeal form. The sheer number of alarming implications that carried was enough to make Dumbledore break into a cold sweat. Thankfully, though, the method Julian had used did not appear to restore a ghost's ability to cast spells, since Helena had possessed no wand at all. 'He likely used that mysterious enchantment method of his,' he thought seriously.
If Julian's enchanting method had once merely been interesting, then in Dumbledore's view it had now crossed over into being dangerous in the wrong hands. He knew, of course, that Julian went to almost paranoid lengths to prevent his methods from leaking out, but that did not change the fact that the knowledge itself represented a serious threat. For now, however, Dumbledore decided that he would place his trust in Julian to keep the world safe from the consequences of his own discoveries. 'And now I must somehow coax this ho-ho out of my office without losing any more of my beard,' he thought with a faint headache.