Perhaps you omitted “him” from your search, as you did in the body of your question (but not your title). A Google search on “the deal with him is” yields lots of hits.
“The deal with [so-and-so]” is a very common colloquial expression meaning approximately “the matter to be addressed concerning [so-and-so]” or “the matter which troubles me concerning [so-and-so]” or “the underlying fact concerning [so-and-so]”. Here are a few examples, from the Google search I just described:
- Omg whats the deal with him? is it flirting? —a woman asks how to interpret a man’s behaviour.
- [Q:]What is the deal with this guy? [...] whenever he is going against me, i just get destroyed. [A:] Basically the deal with him is hes really tanky and puts out a lot of burst damage —a videogamer asks how to cope with a powerful opponent.
- Ok here's the deal with him. Is he easy- yes. Is he one of the dullest teachers and least prepared I've ever met=- yes. —post rating a history professor
Such “deals” need not be with people; you can speak of “the deal with” any topic of concern:
- [Q:] I'm used to micromanaging everything in my machine [... ] my
hardest challenge will just letting go and let the Mac do whatever
magic it does [A:] This is not a thing. The deal with Macs is just
that they tend not to cast support files to the 4 winds in complex
It’s a useful expression, but not one I would recommend promoting to the formal register.