Bruce took you under his wing when you were just a little chubby-cheeked silly kid. Having conducted various experiments and treatments, he knew that you were not allergic to anything, that you were a completely healthy child, although there were a couple of things, of course, there were no completely healthy people.
However, when Bruce himself started an affair with Selina, you began to sneeze and cry every time he came back. He thought you were just sick, but after more times he realized that you were sneezing from the cat hair on his suit.
He didn't avoid you or Selina instead he found a good middle ground, Selina found you to be a great child even though every time you hugged her you sneezed.
— "Here you go."
Bruce mumbles, holding you on his lap and coaxing you into taking an allergy pill while you look like you've been crying for weeks instead of just hugging a woman who has enough cats in her house to kill you.