There was a minor character death on last night's episode of 'Mad Men'

***SPOILERS AHEAD***

Almost 11 months after "Mad Men" paused it's final season, the show finally returned last night with the first of its final episodes.

And after Don Draper (Jon Hamm) and his actress-wife Megan (Jessica Paré) decided to end their marriage in the last episode of the first part of season seven, Sunday's premiere had Draper back to his skirt-chasing ways.

One interesting storyline through the episode is Don's reaction to the death of Rachel Menken (Maggie Siff), an old fling of Don's from back in season 1.

But who is this past character who is suddenly addressed in the new episode?

On Sunday, we saw her appear wearing nothing but a long fur coat in a dream Don has about casting models models for an ad.

The dream motivates Don to look her up. But his secretary later informs him that she recently died. This leads Don to pay his respects at her Shiva. There he meets Rachel's sister, who knows everything about their affair and guilts him for showing up.

When Don later meets a waitress at a diner (Elizabeth Reaser of "Twilight" fame), he ends up having sex with her because she reminds him of Rachel.

Looking back on Don and Rachel's affair, you realize why her death affected him.

We first met Rachel in the pilot episode of the show, looking for advertising for her department store. Don was instantly attracted to her and that only grew when Rachel played coy toward his advances.

Through more business meetings, the two began to connect, which inevitably leads to them beginning to sleep together when Don was still married to Betty (January Jones).

And thanks to Rachel, we finally got our first glimpse into Don's past. In an episode towards the end of the first season, Don reveals to her after making love that his mother was a prostitute and that his father was a drunk.

Then in the second-to-last episode of the season, Don surprises Rachel at her office and asks her to run away with him to California. Telling her, "You know more about me than anyone." But she sees right through him and replies, "This was a dalliance, a cheap affair. You don't want to run away with me, you just want to run away."

We thought that would be the last we would see of Rachel, but in episode five of season two, Don runs into her at a restaurant. But by now Rachel is married and goes by the name Rachel Katz.

In an amazing parting line, Rachel turns to the woman with Don, a client, and says "He's all business, isn't he?"