Yarrow raised his eyebrows. "Hm? Oh. Yes, of course." He shifted, stood, brushed some nonexistent flecks of lint off his natty robes, and then stepped carefully out of the portrait frame. For a few seconds, both portraits stood empty, then Yarrow appeared in the center portrait. He was wearing slightly different clothes in this portrait, and when he sat, he was turned at an angle, showing the prow of his nose in profile.
"Thank you again, Mr. Yarrow," Jackson said, leaning against his desk and crossing his arms. "Although there are exceptions, typically, a portrait only becomes active upon the death of the subject. Technomancy cannot explain to us why this should be, except that it seems to respond to the law of Conservation of Personalities. In other words, one Mr. Cornelius Yarrow at any given moment is, cosmically speaking, sufficient." There was a murmur of suppressed laughter. Yarrow frowned as Jackson continued. "Another factor that comes into play once the subject is deceased is the interactivity between portraits. If there is more than one portrait of an individual, the portraits become connected, sharing a common subject. The result is one mutual portrait that can maneuver at will between its frames. For instance, Mr. Yarrow can visit us at Hogwarts, and then return to his home portrait as he wishes."
James struggled to write all of Jackson's comments down, knowing the professor was notorious for creating test questions out of the least detail of a lecture. He was distracted from the task, however, by thoughts of the portrait of Severus Snape. James risked raising his hand.
Jackson spied him and his eyebrows rose slightly. "A question, Mr. Potter?"
"Yes, sir. Can a portrait ever leave its own frames? Can it, maybe, go over into a different painting?"
Jackson studied James for a moment, his eyebrows still raised. "Excellent question, Mr. Potter. Let us find out, shall we? Mr. Yarrow, may I beg your service once more?"
Yarrow was trying to maintain the pose of his second portrait, which was studious and thoughtful, looking slightly away. His eyes slid to the side, looking out at Jackson. "I suppose so. How else may I help?"
"Are you aware of the painting of the rather odious Mr. Biggles in the frame next to you?"
Mr. Biggles responded to the mention of his name by feigning great shock and shyness. He covered his mouth with one hand and batted his eyes. The tiny clown's head on the end of the cane goggled and blew raspberries. Yarrow sighed. "I am aware of that painting, yes."
"Would you be so kind as to step into his painting for just a moment, sir?"
Yarrow turned to Jackson, his watery eyes magnified behind his spectacles. "Even if that were possible, I don't believe I could bring myself to join his company. I'm sorry."
Jackson nodded, closing his eyes respectfully. "Thank you, yes, I don't blame you, Mr. Yarrow. No, we can see, therefore, that while a much stronger magic is required to create the imago aetaspeculum, it isn't designed to allow the portrait to enter a painting of a purely imaginary subject. It would be, in a sense, like trying to force yourself through a drawing of a door. On the other hand, Mr. Biggles?" The clown jumped up ecstatically at the mention of its name again, then looked at Jackson with a caricature of intense attention. Jackson spread an arm toward the middle frame. "Please join Mr. Yarrow in his portrait, won't you?"
Cornelius Yarrow looked shocked, then horrified, as the clown leaped out of its own painting and into his. Mr. Biggles landed behind Yarrow's chair, grabbing it and nearly rocking Yarrow out of it. Yarrow spluttered as Biggles leered forward, his head over Yarrow's left shoulder, the miniature clown's head cane over his right, blowing raspberries into the man's ear.
"Professor Jackson!" Yarrow exclaimed, his voice rising an octave and trembling on the verge of inaudibility. "I insist you remove this… this fevered imagining from my portrait at once!"
The class erupted into gales of laughter as the clown leaped over Yarrow's shoulder and landed on his lap, throwing both arms around the man's skinny neck. The clown's head cane kissed Yarrow repeatedly on the nose. "Mr. Biggles," Jackson said loudly, "that's enough. Please return to your own painting."
The clown seemed disinclined to obey. He threw himself off Yarrow's lap and hid elaborately behind the man's chair. Biggles' eyes peeped over Yarrow's right shoulder, the miniature head peeped over his left. Yarrow turned and swatted at the clown prissily, as if it were a spider he was loath to touch but anxious to kill. Jackson produced his wand--a twelve-inch length of hickory--from his sleeve and pointed it carefully at the clown's empty frame. "Shall I alter your environment while you are away, Mr. Biggles? You'll need to return to it eventually. Would you prefer to find it stocked with a few more Japanese Thorn Thickets?"
The clown frowned petulantly under its make-up and stood. Sulking, it clambered out of Yarrow's portrait and back into its own frame.
"A simple rule of thumb," Jackson said, watching the clown give him a very enthusiastic nasty look. "A one-dimensional personality can merge into a two-dimensional personality's environment, but not the other way around. Portraits are confined to their own frames, while imaginary subjects can move freely into and through any other painting in their general vicinity. Does that answer your question, Mr. Potter?"
"Yes, sir," James answered, then rushed on. "One more thing, though. Can a portrait ever appear in more than one of its frames at once?"
Jackson smiled at James while simultaneously furrowing his brow. "Your inquisitiveness on the subject knows no bounds, it seems, Mr. Potter. As a matter of fact, that is possible, although it is a rarity. For great wizards, whose portraits have been duplicated many times, there has been known to be some division of the personality, allowing the subject to appear in multiple frames at once. Such is the case with your Albus Dumbledore, as you might guess. This phenomenon is very difficult to measure and, of course, depends entirely on the skill of the witch or wizard whose likeness appears in the portrait. Is that all, Mr. Potter?"
"Professor Jackson, sir?" a different voice asked. James turned to see Philia Goyle near the back, her hand raised.
"Yes, Miss Goyle," Jackson said, sighing.
"If I understand correctly, the portrait knows everything that the subject knew, yes?"
"I believe that is apparent, Miss Goyle. The painting reflects the personality, knowledge, and experiences of the subject. No more and no less."
"Does a portrait, then, make its subject immortal?" Philia asked. Her face, as always, was stoic and impassive.
"I am afraid you are confusing what appears to be with what is, Miss Goyle," Jackson said, eyeing Philia closely, "and that is a dreadful mistake for a witch to make. Much of magic, and much of life in general, I might add, is concerned primarily with illusion. The ability to separate illusion from reality is one of the fundamental basics of technomancy. No, a portrait is merely a representation of the once-living subject, no more alive than your own shadow where it falls on the ground. It can in no way be thought to prolong the life of the deceased subject. Despite all appearances, a wizard portrait is still merely paint on canvas."