Mad Men Season 4 question -- open spoilers

I’m watching on DVD, and just watched the 11th (of 13) episodes – will finish tonight, but please don’t spoil the season finale for me!

But, we’re in the “wheels coming off” section:
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Starting with the feds wanting to investigate Don – well, the whole team. But it is obvious that Pete knows Don’s secret – and I have zero recollection of the circumstances under which he found out. Must’ve been last season … why does he know?

Don’s half brother tracked him down & left him a package of pictures & other incriminating details about his secret identity. Pete intercepted it. Then Don made him feel insulted; maybe he passed him over for a promotion. So Pete marched into Bertram Cooper’s office & told him that Don was not really Don.

Bertram’s response: “Who cares?”

There’s more to it but that’s my immediate memory. (And I think this happened in the first season.)

That could be why I don’t remember – season 1 is a long time ago. Is that why Pete came with them to the new firm? Is he still more or less blackmailing Don?

No. Don approached Pete, because they needed his accounts to get the new company afloat, and because his insights were ahead of the curve.

I think Matthew Weiner said in an interview something about how Pete is often right, because, for one thing, he actually reads the results of the market research. There was one campaign where he advised the client to advertise in the black media, because it was cheap and there was an untapped market there.

Ah, right, okay. And that’s why the other guy is trying to recruit him.

Pete comes from Old Money or something approaching it. He’s the only one at the firm with this distinction. It’s not so much that having him around makes the firm look good, as that having no blue blood on the upper deck makes them unappealing to desirable clients. They overlook a lot by keeping him on, but he provides something necessary just by being on staff.