Two and a Half Men was one of the biggest, if not the biggest, sitcoms on television for many years. Airing for 12 seasons from 2003 through to 2015, a lot changed throughout the series. Most noticeably, the biggest change was the departure of lead character Charlie Harper, played by Charlie Sheen, after the eighth season. He was replaced by Ashton Kutcher.

But looking way back to season one, it's easy to forget how it all began. The series was about Charlie, a wealthy and womanizing bachelor, who finds his brother Alan knocking down his door after his wife kicks him out of the house. Along with Alan is his precocious 10-year-old son Jake.

RELATED: Two & A Half Men: 10 Things That Make No Sense About Alan 

Charlie has no interest in having a family nor caring for a child but can't turn his brother away when he has nowhere else to go. So how do things progress?

Charlie Let Jake Play Poker

Jake Alan Charlie

In the pilot episode, after Alan leaves Jake with Charlie for the first time, he comes home to discover that Charlie had let Jake play poker, definitely something totally inappropriate for a 10-year-old.

This was the move that prompted Alan to take Jake to live with his mother instead. But when Jake expresses his love for his uncle, Alan has a change of heart.

Rose Glues Charlie's Cabinets Shut

Rose from Two and a Half Men looking concerned

When Alan first meets Rose, he thinks she's the housekeeper, one of her first lies to Alan before he realizes who she really is. Rose, of course, had a one-night stand with Charlie and had been stalking him ever since.

On this occasion, also in the pilot episode, she glues all of Charlie's cabinets shut as part of her long and ongoing plan for revenge.

Alan Tried To Get Judith Back

Judith in a green printed top looking at Alan at Judith's Door in Two and a Half Men

In the later seasons, it's clear the marriage is over between Alan and Judith. They are both dating other people and while they still clearly don't really like one another, they get along fine as co-parents.

RELATED: Two and a Half Men: 10 Things That Make No Sense About Jake

But it's easy to forget that in the first season, Alan was actually trying to get back together with Judith. He would go to the house and fix things that were broken. But in the end, he actually cut romantic ties with her for good.

Berta Quits

It's hard to ever imagine Charlie being able to live without Berta, who dutifully cleaned house for him (and later for Walden). In the first season, Alan continually criticized Berta's work, causing her to quit. Alan says he will take over but he doesn't have Berta's touch for doing things like making Charlie's coffee "Christmas-sy."

Alan tries to get Berta to come back and eventually she does, saving Charlie from having a piano that smells like lemon Pledge and non-festive coffee.

Charlie Teaches Jake About Breast Augmentation

two and a half men judith alan jake

In one episode when Judith gets upset that Jake is drawing photos of a tattooed butt, owned by a female friend who walks around Charlie's place half-naked, she has to have a talk with him about it.

But more interesting is the talk Charlie has with Jake about breast augmentation, and real breasts versus fake. Armed with this knowledge, Jake is excited to compare them any time he gets the chance.

That Awkward Thanksgiving Dinner

Evelyn Harper smiles while in Charlie's kitchen in Two and a Half Men

In an effort to prove to his ex-girlfriend Lisa (played by Denise Richards) that he is a family man, Charlie hosts a Thanksgiving dinner with his family. As in the whole family. That includes Alan and Jake, his mother Evelyn, and Judith and her parents.

RELATED: Two And A Half Men: 10 Things About Alan That Would Never Fly Today

Things get awkward when Evelyn reveals to Judith's parents that Judith is gay and her parents take Alan's side in the divorce.

Megan Fox Guest Starred

two and a half men megan fox

that time Megan Fox guest starred on the show? She played Berta's 16-year-old granddaughter Prudence who had to come to work with her grandmother. Not surprisingly, Jake develops a crush on her.

Prudence later tries to get into bed with Charlie the night before her wedding in Las Vegas, but thankfully, Berta jumps in and stops her.

Charlie Has Money Problems

Money seems to be the least of Charlie's problems as a successful jingle writer who gets paid by a constant stream of royalties. Except one day, his credit card gets declined and his ant tells him he spends money faster than it comes in.

Alan than tries to teach Charlie how to manage his money and spending better, and Charlie ends up borrowing money from Rose to get him out of a jam.

Jenna Elfman Was On The Show

Elfman appeared on two episodes as a woman on the run with her 8-year-old daughter who at first grabs the attention of Charlie but then sparks up a romance with Alan. She ends up leaving after spending the night with him.

But she leaves her bra for him to her by and Alan is once again alone and looking for love.

Alan Names Charlie Jake's Guardian

Charlie in a maroon bowling shirt hugging Jake on a couch in Two and a Half Men

Alan initially appoints his cousins from Rhode Island as Jake's guardians in the event that both he and Judith away. This offends Charlie despite his not really wanting children of his own.

After Charlie accidentally injures Jake but then takes him to the hospital and cares for him like a parent, Alan realizes Charlie is up for the task after all and names him Jake's guardian.

NEXT: Two And A Half Men: 10 Things About Rose That Would Never Fly Today