Dobby looked at Oleandra with upturned, puppy-dog eyes. Under a Full Body-Bind Curse, the eyes were the only part of the body still capable of movement, so he was making full use of their range of motion to signal that he wanted out.
"Oh, very well," Oleandra sighed. "Blink twice if you won't bolt the instant I set you free. There are a few questions I'd like to ask you."
Dobby began blinking as fast as he could manage, which was not what Oleandra had instructed, but since her Mystic Eyes detected no falsehood behind his frantic fluttering, she decided to free him. She grabbed a quill from her desk, dipped it in ink, and added a flourish to the Dagaz rune that Loki had carved into his back, countermanding the hourglass rune's magic that had caused the Full Body-Bind to cycle infinitely, and accelerating the cycle to its natural conclusion.
"Oh, thank you, thank you, Mistress Greengrass!" Dobby blubbered as he thawed, hopping down from Oleandra's desk to bury his snotty nose in the hem of her robes and hug her shins. "Dobby had almost given up hope for his freedom— oh yes, Dobby had indeed!"
"Er, that's all right," Oleandra said, slightly taken aback by the obvious awe he held for her. "I'm not that great a person, really. Oh, hang on, I need to treat your back, it's going to get infected…"
Dobby blew his nose loudly and wiped the tears from his eyes, only to erupt into fresh cries, his small, wiry torso shaking with sobs.
"Mistress Greengrass is a great person, greater than even Harry Potter himself!" Dobby cried. "She remembered Dobby's name! She campaigned to free the House Elves in the kitchens! She defeated the Dark Lord more than once! Dobby heard all about her exploits during his time at Malfoy Manor, Dobby did! Only Dobby knows she is innocent of all the crimes she is being accused of!"
Even if it was only from a lowly House-Elf, it did Oleandra some good to know that at least one person still believed in her. Still, she kept her guard up. For all she knew, Dobby's rescue was merely a part of some larger scheme of Loki's…
"How did you end up hanging above Lo— I mean, above your master's bed?" Oleandra asked, scooping out some thick paste from an ointment she had brewed in Slughorn's potions class and slathering the vulnerary over his wound, muttering under her breath, "Saille."
Dobby shuddered.
"Young Master Draco is no longer Dobby's Master Draco," he corrected her. "Master gave Dobby his freedom when he gave Dobby his Invisibility Cloak…"
Hot tears began dripping from his eyes once more.
"But it was all just a cruel trick!" Dobby howled. "Master never intended to give Dobby his freedom! Master just wanted to offer Dobby a glimpse of hope… and then snatch it away!"
Evidently, Loki must have noticed how much Dobby yearned for freedom and decided to set him free by giving him Harry's Invisibility Cloak, technically a piece of clothing. Then, when Dobby was overcome with joy, he'd doubtlessly petrified him— ironically, giving him what he had always wanted, but placing it just beyond his reach.
At the same time, as a living being, Dobby served as the perfect hiding place for the True Invisibility Cloak's unparalleled stealth magic. While in use, it was almost impossible to detect… but was sacrificing a perfectly good House-Elf really worth securing a good hiding place? To Oleandra, it didn't make much sense…
…and then the answer dawned on her.
"I see… so that's how it is!" she muttered to herself, covering her mouth with her hand. "It's not that Loki enjoys playing pranks… it's that he's physically incapable of holding back his true nature…!"
The twenty-four runes branded on Oleandra's soul served two purposes: they allowed her to synchronise with the constellations in the night sky, granting her the magic of the stars and bypassing the need for years of rune-engraving practice; and they transformed her into a beacon, a lightning rod through which the Aesir's souls could descend from the heavens and use her body as a vessel on Earth.
To transcend death, the Aesir tribe of wizards had converted their souls into pure information and stored them in the heavens, using stars as neurons and constellations as neural pathways. This had granted them the right to bar other wizards on Earth from using star magic without permission— thereby causing the decline of ancient runic magic. By what miracle they had achieved this, Oleandra did not know; but what she did know was that the realm of souls was not something to be trifled with.
"A boon always demands a return…" Oleandra whispered. "They paid the ultimate price to achieve immortality!"
Each time the Aesir's souls descended, they lost a little more of themselves; their souls tainted by their hosts, and seemingly meaningless information lost in the conversion from soul to star or the transfer from star to human brain. Over time, they gradually must have transformed, no, degenerated, into mere lumps of pure obsession, the cores of their personalities.
Odin was obsessed with knowledge.
Thor was obsessed with strength.
Loki was obsessed with pranks.
In the end, the Aesir were not gods, but something lesser and meaner than even the basest Muggle. Though Loki must have lived for thousands of Oleandra's lifetimes, she doubted he could have learned much from those years. He was not as invulnerable as she had once believed, because his obsession made him predictable. She could exploit that weakness to rid herself of him forever.
If Oleandra could somehow convince Loki that she'd fallen for one of his tricks, she would be able to reverse his trap. Even though she had already obtained what she needed from him, Harry's Invisibility Cloak, she felt like he was still too dangerous to be left to his own devices.
Or at least, that's what she told herself. With all three Deathly Hallows in her possession at once— a first in Wizarding history— the only thing left to do was gain the Elder Wand's recognition. But Oleandra felt it was too soon, far too soon. She hadn't expected to succeed so easily, and she'd hoped for one last year to spend in her twin sister's company, at the very least…
"There you go, all better now— your wound shouldn't trouble you any more," Oleandra said, rubbing potion residue from her hands with a tissue. "So, what will you do now with your freedom, Dobby?"
Dobby started. He hadn't thought about that yet, but the more he did, the more frightened he became. The British Isles had fallen to darkness, and there was little a free House-Elf could hope to achieve under such conditions…
"If it's not too much to ask," Dobby whimpered, "could Dobby please ask Mistress Greengrass for a job?"