vesper 1 is Dave Speimner aka Riley Mcgrath . isabel's mother's maiden name was vesper . also ,she is more dangerous than a cahill , which is how she became a vesper .
Isabel was never a Vesper before Vespers Rising. She was ignorant to Cahill existance before she met Vikram and Irina.
Isabel's maden name was Vesper (So it's Isabel Vesper-Kabra) it was never confirmed or denied that she was part of the actual vesper bloodline, but her last name suggests she was.
I agree with Brendon because in Operation Trinity Isabel Kabra tries to destroy the Ghent altarpieace which is suppose to be somehow tied into to the locations of the clues , but Grace stops her before she can.
What do you think?