Emma got into a car accident and the show "Once Upon A Time" is just a collection of dreams Emma has been having while she is in a coma. Her dreams are altered versions of her memories. In reality she is married to Regina and Henry is their son.
Emma's parents didn't approve of their relationship at first so they disowned her and that's why in her dreams they sent her to a wardrobe. Eventually they came around learned to accept her and in her dreams the curse is broken and Mary Margaret and David remembered Emma is their daughter.
Regina's mother Cora was obsessed with trying to find Regina a rich, successful husband. Cora was against Regina and Daniel's relationship because he was a poor stable boy. This often caused fights between mother and daughter. Regina often cried to her father but he too afraid of her mother to do anything about it. One day Cora pretended to be okay with Regina's relationship in Daniel. She proposed a toast where she secretly snuck Viagra and Nitroglycerin, a deadly mix, into Daniel's drink and Daniel died in Regina's arms. Regina vented to her father and out of her rage accused her father of being a failure at being a father because he never defended Regina against Cora. Her father was so upset over Regina's harsh words so he ended up dying of a heart attack. Cora would eventually stop her obsession with Regina's love life and would accept whomever Regina wanted to be with. However she died of heart failure before she could see Regina marry Emma.
Emma would often dream about Regina and her making magic together, which were in reality them working on a case together. All of the villains in her dream were criminals in reality. Pan was Mr. Gold's father who could not grasp the reality of adulthood so he would kidnap children and forced them to be his friends. After tragically losing her sisters, Ingrid tried to force Elsa and Emma to be her sisters instead. When they rejected her, Ingrid committed suicide. Cruella abused animals and fell off a cliff trying to chase one of her dogs that got loose. Emma's dream of Mal's sleeping curse is actually roofies. Mal was a drug dealer. Mal's magical powers in Emma's dreams were different drugs she would manufacturer and sell. Ursula used to be a cruise ship singer but was fired when she lost her voice so she became a pirate who would steal from ships and wasn't afraid to kill anyone who got in her way. As they worked on cases together, Regina and Emma grew close and ended up falling in love.
Mr. Gold was an officer in the Navy and Killian Jones was his Captain. Mr. Gold was scared to fight in the front lines so he shot himself in the foot so Captain Jones gave him a dishonorably discharge. This is also why Mr. Gold has a cane and limps. This caused his wife, Milah to be ashamed of him and left Gold for Captain Killian who bravely lost his hand during the war and now has a prosthetic hand. As a result, Mr. Gold became addicted to alcohol instead of power in Emma's dream. Because of this, Neal ran away from home. Since, Milah left, there was no one to keep his house tidy so he hired a maid named Lacey who always saw the best of him and helped him with his addiction.
When Regina and Emma decided it was time for them to have a baby, they turned to Mr. Gold.
Regina said to Mr. Gold, "Emma and I want a child and we need your help"
Mr. Gold responded, "I'm flattered but I'm not interested."
"No! Not like that. We need a sperm donor."
Mr. Gold responded with "If you want my help, you both owe me a favor because dearies my help comes with a price."
Emma and Regina agreed to reunite Gold with his long lost son Neal and in return, Mr. Gold persuaded Neal to be Emma's sperm donor, which is why in her dreams he didn't really know about Henry and left Emma.
Regina became busy with her campaigning for Mayor while running against a very formidable foe, Arthur, which is why in Emma's dreams she was neglectful of Henry. Her subconscious mind wanted to blame their rocky marriage on Regina so she dreamt her, as the Evil Queen and Emma was the savior because she wanted to save their marriage. Things got difficult so Emma got tempted and turned to Killian, who left Milah for Emma.
Regina felt bad about not being there enough for her family so she wanted to change, which is why she eventually stopped being the Evil Queen in Emma's dream. When she wanted to surprise Emma at the police station with lunch, she caught Emma cheating on her with Killian. She walks off like a woman scorned. Emma felt bad about cheating on Regina, which is why eventually in her dream, she became the "dark one"
She decides to head to a local bar to take her mind off Emma. Robin spots her from across the room so he gets his sister, Tinkerbelle, to be his wingman and set things up. Tinkerbelle sits next to Regina and pretends to be a fortuneteller and tells Regina that the cards indicate her soul mate has a lion tattoo, which Robin happens to have on his wrist. Robin became Regina's rebound.
Tinkerbelle later found out that Regina is already married so she tried the same scam on Regina's sister Zelena. Zelena was so desperate to be with her soul mate that she drugged Robin and became pregnant with his child. This caused Regina and Zelena to be bitter enemies. This also caused tension with Robin's relationship with Regina.