From the detection spell, what Vali could detect were essentially three abilities.
The first and probably the most visible one was some bastardized version of shapeshifting, which should allow the user to change his facial features and, in the advanced stages of the ability, even alter the physique.
From his point of view, in the current state, it wasn't that useful, but it was something with which they could work. The second ability was something that was partially interested him, as it was the ability to speak to serpents, which could be considered a Magic Language.
Magic Languages were rare because each word considered some sort of power and if the person was casting spells in the Magic Languages, their effect and power would be greatly increased. And the third one was...
"It appears that your Bloodline makes you mostly immune to the effect of the various types of Curses... or rather, you can cast them without suffering any side effect, which is... mind blogging at least to say."
This was something that could be considered by some even rarer and more powerful than any Clan Trait.
Usually, curses were a peculiar bunch of magic because to use curses, one needed to sacrifice something; essentially, the curses worked on the principle tit for tat; nothing was free in the world.
"I am sure that even my father would be interested in studying your blood..."
Vali muttered as Arcturus Black was in a deep thought, as he was thinking about the things that Vali said, while he was aware that the Black lineage contained some bits of the Slytherin's and Gaunt's bloodlines, which would explain the Parseltongue...
But the immunity to the side effects of the Dark Magic was new.
Or rather, it was old new.
Nobody from the Blacks has ever contemplated about it too deeply, as they shrugged it off as an affinity for the Dark Magic, not considering it as anything that great, but it probably appeared to be the exact opposite.
"You probably aren't even aware of the true extent of your ability, right?"
Vali asked more rhetorically as he saw that the House of Black if they were to be established as a full-fledged Noble House in the Chthonian Empire, would need to put a lot more effort into it.
Especially if at least some of them mastered several of the most forbidden curses that were in the repertoires of the Chthonian Empire, then the Blacks would be a force to be reckoned with.
***
After Vali finished the discussion with the Arcuturs Black, he departed to find his granddaughter while the man in question was having a discussion with Abraxas Malfoy and Tom Riddle about the support of the House Black for the Knights of the Walpurgis Order, but Vali didn't need to be present there for that as that was not his matters.
He rather preferred to have a "duel" with Bellatrix Black, as he wanted to have some grasp on her personality.
When he found the young woman, he noticed that she was in the library, reading some books on battle magic.
Blacks had evidently one of the biggest private-held magic libraries in the world; among the Noble Houses, probably only a few Houses had bigger private libraries in their possession.
Naturally, the part which was on the Number 12 Grimmauld Place was only a part of it, as the majority was on the castle, which was owned by the Black Family.
"I see that you are a bit bookworm, Miss Black."
Vali stated with a smile, which caused Bellatrix to blush mildly because this was the first time she saw as handsome a man as him.
True the Lucifer and Gremory genes were the epitome of beauty and when he thought over it, all devils, even the common ones, had unnatural or rather supernatural beauty in the hands of mortals.
"Hello, Mr. Amaranth; I take that you finished your discussion with my grandfather."
Vali nodded, making the young woman curious about what they were talking about.
Her grandfather was politically speaking very powerful man, and even till this day, he was still Head of the House Black and still held the seat of their family on the Wizengamot.
Though she knew that it was mainly because he thought of his son Orion, her uncle, as a spinless coward who couldn't be trusted with even a mug of goblin piss.
"You may call me Vali."
He stated, which caused the young Bellatrix to smile as she nodded.
"Then call me Bellatrix."
She said as she closed the book she was reading before standing from her chair and heading towards the dueling room, as Vali followed after her because he knew that it was time for their duel already.
The dueling room was located beneath Number 12 Grimmauld Place and it was well-warded by the standards of the Wizardcraft Magic.
Among many of the Noble Houses, such Dueling Rooms within their properties were relatively common and could be seen rather easily.
Naturally, the one that belonged to the House of Black was top-notch, as while Vali was observing the Dueling Room, Bellatrix changed to something more suitable for combat as he then checked her out in the battle outfit, which didn't escape her attention.
"Are you done checking me out?"
She asked with pretended irritation when she noticed that he was checking her out, something that indeed stroked her ego a bit.
"For instance, no, but I can always continue during the combat."
He answered with a grin as he dodged to the right side, missing some random curse that his opponent cast at him without warning.
Seeing this, he revealed a feral grin and actually was happy because another person understood how the "real duels" should be fought.