Hello to you! Here’s one of my fave portrait-claims yes I invented that word just now of Paul:

[by Philip Alexius de Laszlo, Portrait of Raymond P. Johnson-Ferguson, 1923]
Paul is in fact mentioned by name in IWTV, but it’s only 3 times, and the first time is on page 26 (US Ballantine edition):
“I could almost make out the images of the saints on the walls. `Paul,’ I said softly, addressing my brother, `for the first time in my life I feel nothing for you,…” – Louis de Pointe du Lac, IWTV
…so if you were skimming a physical copy, it would in fact be hard to find the mentions at all! I have digital copies of all the books, makes for easier searching ;]
The first time Paul is mentioned, it isn’t by name at all, on the 2nd page. Paul was a big deal for Louis and he has to bring it up immediately.
“There was a tragedy … “ the vampire started. “It was my younger brother … He died.” – Louis de Pointe du Lac, IWTV
Would Louis have been in such a crappy state and basically trying to drink himself to death, shouting “COME FIGHT ME BRO” at everyone in the shittiest taverns of NOLA if not for his guilt over Paul? Would he still have met Lestat at some fancy ball? WHO KNOWS.