User blog comment:B214/Question and Answers 6/@comment-24098614-20170927012228/@comment-10330822-20170927040941

I don't know about that FANDOM user, the reason Rias was drawn to Issei was because he had her posting and his "strong desire" to see a beautiful woman is what drew Rias to him, it wasn't like Rias was specifically targeting him in the first place, she kind of just "happened upon him".

She seemed to originally just plan to make him one of her eight pawns, but was surprised when he required all eight, a sign that he had incredible potential.

Now, if you go further back, the reason Rias had to save Issei at all was because Raynare killed him "because" he had a Sacred Gear.

In other words, had Issei not had BG, then Raynare wouldn't have killed him, and then his desire wouldn't have drawn Rias to him, because she wouldn't have been assigned to spy on him was because his SG was a threat to the Grigori in the first place.