While Megan isn't an original character from the start of Mad Men, once she joins the cast it doesn't take long for her to become a main character. Quickly ending up in a relationship with Don, which turns into a marriage and instantly makes her the center of attention for many storylines.

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However, that doesn't necessarily mean that she is always a fantastic character. While Megan starts out very vibrant and with tons of personality, that does change throughout the series, and many diehard fans argue that she got worse as the show went on.

10 She Thinks Advertising Is Beneath Her

It is through advertising that Megan Draper gets her big break in life, but she quickly ends up looking down on the industry, mainly because she can't climb to a top-level. She hates being judged for simply being Don's wife in the office and it gives her a negative view of the industry.

She's judgemental of the vast majority of the people that work in the office and despite originally loving that world, it quickly ends up changing for her.

9 She Becomes A Pushover

The big reason that fans bought into the romance between Megan and Don is that it seemed like she was going to change him for the better. At first, she managed to keep Don in line and when he was wrong, she made sure he was aware of it.

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However, as the series went on and Don's behavior didn't really improve, she ended up becoming a shell of her former self. Instead of putting Don in line, Megan just fell into the same behavior patterns as Betty Draper and went along with whatever he wanted.

8 Hating Her Mother's Happiness

Another way that Megan gets worse is how she treats her mother. The fact her mother is willing to constantly travel to see and help her shows how much she cares, but Megan seldom gives that respect back to her. She is often rude to her mother and barely gives her any respect.

This is clear with her disapproval of her relationship with Roger Sterling, despite the fact that she is clearly unhappy with her father and the total opposite of him. Megan acts like a spoiled brat at times with her mother, which is a poor character trait.

7 She Becomes Self-Pitying

While Megan starts out very happy, working hard for everything she gets and always trying to put a positive spin on things going on in her life, that quickly changes. This is particularly true once she gets into the acting industry.

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Megan falls into a rut of self-pity where she never seems to take any responsibility for her career, particularly when her acting skills are actually criticized. It's a shame because that is one characteristic that she never used to have but really does develop about every minor detail.

6 Becomes Spiteful

Even throughout her time being angry with Don Draper, she normally never loses her cool for too long, but as the series goes on she ends up becoming very spiteful of different people. Whether it be the success of Don in work and the fact it takes up his time, or because she has very few friends.

She ends up being spiteful of everyone, particularly when she moves to LA. She becomes lonely but rather than admitting it and talking to people, she just loses all sense of purpose and opts for drinking and parties to fulfill her needs.

5 Stops Being A Good Stepmom

When Megan first starts her relationship with Don, she is fully aware of the commitment she is picking up due to him already having three children. She's great with the children at first, particularly Sally, who instantly begins to look up to her.

Megan does what Betty doesn't, in the fact that she actually spends time with them and tries to connect. However, that all changes when her career begins to take off, and at that point, the children become a burden. She leaves them on their own at times and it leads to a major moment when she stops paying attention to Sally and she meets Glen in the city.

4 Becomes A Stereotypical Actress

Speaking of Megan's career taking off, it is through that where she really does begin to change as a character, and not in a positive light. She wanted it so badly that other things in her life end up taking a backseat such as friends and loved ones.

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She doesn't care about anything other than her career and it starts to make her self centered. That was a total change of attitude from how she first started, which didn't make her a more compelling character at all.

3 Becoming Jealous

While Don Draper certainly plays a part in making Megan jealous due to his adultering behavior, Megan's jealousy does end up getting the best of her. She becomes paranoid over every little detail and it takes away the confident and sassy attitude that made her great in the first place.

This is never more clear than when Stephanie goes to Megan's house. She is likey family to Don and he is desperate to see her and how she is doing while pregnant, yet all Megan thinks is that Don is the one who impregnated her as she just gives her money and sends her off.

2 She Becomes Boring

While this might be a case of the writers not creating enough engaging content for her, the fact is that her character does become really boring. The reason she was so fun in the beginning is that she brought a real zest of life and energy that Don's character really needed.

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But as the series wore on, Megan's energy levels drop and the scenes she has are no longer as interesting. She appears in the show less frequently and whenever she does appear it's always in a moody way. This is why she didn't get a big ending on the series, which is a shame.

1 She Becomes Ungrateful

The worst way Megan changes is the fact she becomes incredibly ungrateful when she speaks with Don at the end. Sure, divorce isn't easy and it certainly is something that brings out the worst in people, but Megan's lack of gratitude for everything Don has done for her is staggering.

He paid for her home, supported her dreams of becoming an actress and completely changed her life by taking her from someone working on the reception desk to a bonified actress. He even gives her $1 million and that is something she can't even be happy with.

NEXT: Mad Men: 10 People Don Should Have Been With (Other Than Megan)