Ah, Jan Levinson. As the former Vice President of Northeastern Sales for Dunder Mifflin, Jan visited the Scranton branch often thanks to the corporate offices only being two hours away in New York City. Due to her gorgeous looks and love for authority, Michael Scott developed a crush on Jan every time he saw her.
Jan never gave Michael the time of day until she got drunk at a local Chilli's while on a business meeting with Michael. From there on, their relationship on The Office was pretty physical, with these two sneaking around to sleep with one another without anyone at work knowing. As we find out, though, Jan and Michael have stark differences in views of their relationship. Michael wants to tell the world while Jan wanted them to be a secret. Michael wanted to be cuddled while Jan didn't believe in public affection.
This relationship came tumbling down on the night of their dinner party but it was for the best. As we can see from this article, Jan had some terrible moments on The Office and these were just the half of it.
WENT BEHIND MICHAEL'S BACK DURING HER DEPOSITION
In the eighth episode of the fourth season, Jan is suing Dunder Mifflin for wrongful termination. Michael was excited to be by his girlfriend's side for the deposition because she was going to get a lot of money if she won the suit.
What Michael didn't know was that Jan went behind his back and gave him horrendous reviews and work and downplayed their relationship. You can see how hurt Michael becomes and in a change of heart decides to defend Dunder Mifflin instead of Jan. Unlike Jan, Michael is loyal to Dunder Mifflin.
SHE MAKES MICHAEL SLEEP AT THE END OF THE BED
"Dinner Party" is quite honestly one of the funniest episodes The Office ever filmed. Also in the fourth season, Michael and Jan invite Pam, Jim, Angela, and Andy to their home for a dinner party (Dwight ends up coming by last minute, which infuriates Jan). Jan and Michael decide to give the gang a tour of their condo when Micahel points out that he sleeps on the ottoman at the bottom of their bed. "Jan has some space issues so I crawl up on that puppy," he sadly explains.
WHEN SHE CHOSE A SPERM DONOR INSTEAD OF CHOOSING MICHAEL
In the episode "Goodbye, Toby," Michael not only realizes that he has feelings for his new HR rep, Holly, but that his ex-girlfriend, Jan, is pregnant!
After seeing her baby bump at the grocery store, Micahel assumes the baby is his because they haven't been broken up that long. Sadly, Jan admits the baby's not his... She went to a top-of-the-line sperm bank to make sure her child had an actual shot...
AND THEN SHE GAVE BIRTH WITHOUT TELLING HIM
Even though Michael knew Jan went behind his back to choose sperm that wasn't his, he desperately wanted to be a father and this little baby seemed like his closest shot. The only problem was he had no connection to the baby whatsoever, but that did seem to matter. Michael and Dwight prepared themselves for the day of Jan's labor. When the baby came, Michael would be ready.
To show his support for this baby (that wasn't his), he and the office threw a baby shower. Their plans went to Hell when Jan walked through that door with the actual baby... When her water broke, she didn't even have the decency to tell Michael!
WHEN SHE TRIED TO HIDE MICHAEL FROM HER COLLEAGUES
When Jan and Michael first hooked up in Jamaica, he was so excited that he "accidentally" told everyone. Jan was so upset she literally drove two hours to have a discussion with Michael. It was then that we learn Jan wants to fully embrace their weird connection and to actually become a couple.
The only problem was when Jan was invited to a corporate dinner party, we learn that she's embarrassed to tell everyone she and Michael are in a real relationship. She liked it better when it was a secret and felt wrong. This greatly upset Michael and he left the party in tears.
SHE TOOK ADVANTAGE OF MICHAEL'S PAYCHECK
When Jan was fired from Dunder Mifflin, she was on a downward spiral. Working was her life and something she was proud of. However, her erratic behavior and lack of desire proved offensive to Dunder Mifflin's CFO. With nowhere to go, Jan moves from New York to Scranton to live with Michael. She laughs (and cries) at the idea of her being the homemaker while Michael went to work. Sadly, Jan took advantage of the situation and blew through most of Michael's money. She made them sell their cars to get a nicer one, she redid the condo at Michael's expense, and then when Michael decides to file for bankruptcy, Jan scolds him for being irresponsible! All in all, Jan was the irresponsible one for blowing through Michael's money knowing well enough what he was making.
WHEN SHE TOLD MICHAEL NOT TO DATE HOLLY
As if getting pregnant from gold sperm and having the baby without telling Michael wasn't heartbreaking enough, Jan tells Michael not to date Holly as she's leaving her own baby shower. It was a twisted request coming from someone who belittled and abused him for months. Deep down, we all knew Michael loved Holly and that Jan would be jealous, so for her to make such a bold request was a low blow.
SHE TRASHED MICHAEL'S DUNDIE!
Any avid viewer of The Office knows how important Michael's Dundies are to him. Created by himself, a Dundie is an award given out to the best of the best at Dunder Mifflin Scranton. Unlike some of the other workers, Michael actually enjoys going to work every day and calls his co-workers his family. His Dundies are as special to him as his job is.
In the same "Dinner Party" episode, Jan—in a fit of rage—grabs Michael's Dundie and chucks it at his "plasma" flatscreen TV. Not only did his beloved TV break but so did his prized Dundie.
SHE USES DUNDER MIFFLIN'S INTERN AS HER LITTLE TOY
We finally see a few fresh faces in The Office once Michael leaves Dunder Mifflin behind. Adding two interns to their branch, Dwight becomes semi-attached to the one intern, Clark. Seeing as the two men kind of look alike (glasses and brown hair), Dwight takes Clark with him on a few sales calls to portray a father and son sales duo.
After preparing to pitch to the White Pages, Dwight finds out Jan is the new CEO. Knowing her appetite for younger men, Dwight practically auctions Clark off to Jan as she tells him to "spin around" to have a better look. Jan promises to give Dunder Mifflin their business as long she can "keep" Clark for herself. In short: he came back to Dunder Mifflin scarred.
WHEN SHE ASSUMED MICHAEL GOT HER DRUNK ON PURPOSE
On the night of Michael and Jan's first kiss, they were a little drunk after spending the night at a business meeting at Chilli's. Jan made the first move after realizing Michael isn't as dumb as he acts and the two were last seen leaving together. The following day, Jan calls Michael and blames him for them spending the night together. We can hear her asking if he intentionally got her drunk to make her kiss him... Michael handles the backlash pretty well considering, but it was a cold move to blame someone else on her own feelings.