Relationships
A main theme of the show is Alan and his brother's contrasting abilities, including his brother's success in dating. Alan is very awkward when it comes to women, and he has had several long-term relationships end badly. This makes him the polar opposite of his brother Charlie, who can get any girl he wants but rarely sees women after he sleeps with them (though he also had some longer relationships conclude in a rather unhappy fashion). Charlie's housekeeper, Berta, described Alan as "the only man who can drive any woman out of Charlie's house." This theory was proven when Charlie was afraid of his attraction to Chelsea's gorgeous friend Gail, and falsely told Alan he had a shot with her; after Alan flirted with Gail, she fled the house in horror and Charlie's temptation was gone.
As a child Alan was often the victim of bullying and got no help from Charlie since his brother participated in much of it. Not much is known about his relationship with their father since he died from food poisoning when they were young, after Evelyn served him spoiled fish that had been stored in a drawer.
Alan used to be married to Judith (Marin Hinkle), the mother of their son Jake; after they divorced, Alan got stuck with paying her $3875 monthly alimony, thus forcing Alan to move in with brother Charlie at the onset of the series. Judith lived a luxurious life on Alan's alimony until she married Dr. Herb Melnick (Ryan Stiles), Jake's pediatrician (also known as Greg Melnick in earlier episodes). Alan was so overjoyed at the end of his alimony requirement that he had a large cardboard check made for her for the last payment. Following the wedding, he only had to pay child support, which Judith does not need but gladly takes from Alan to keep him miserable.
Alan's second wife Kandi (April Bowlby) was one of Charlie's former girlfriends. She was so incredibly stupid she made Jake look like an intellectual. In the divorce, she received the condominium they bought with casino winnings after their impromptu Las Vegas wedding.
Alan went to California State University at Long Beach, but failed to get into medical school. He studied chiropractic in Guadalajara with almost no Spanish language skill. Alan had wanted to be a doctor, but he could not get into medical school, and Evelyn did not help him because she did not think he was worth it.
While he loves his brother and son, Alan resents Charlie somewhat, mostly because everything (money, women) just seems to fall into Charlie's lap, while Alan has worked hard his whole life only to remain a failure and has yet to reap such rewards. (Alan notes at the beginning of Season 8 that just one of Charlie's monthly royalty checks for his children's songs is more than he makes in a year.) Although he and his brother do have a sometimes tense relationship, they remain loyal to one another with Charlie able to cheer Alan up when he needs it, or Alan having to control Charlie's free spending ways when it damages his finances. He has little confidence in Jake, mostly because of the boy's lazy, unmotivated attitude, but he does love his son.
Alan also gets little sympathy even when he's had terrible misfortunes befall him. When he fell off the roof while fixing a satellite dish and was severely injured, he got little sympathy from Charlie, Judith, or Evelyn. He has also had to suffer torments caused by Charlie's behavior. He also got no sympathy after his second divorce.
Generally a nice guy, Alan has displayed some bad behavior and sneaky motives. When Charlie was going to couples-counseling with Chelsea, he fed Charlie a bunch of false information from conversations with her, and Charlie ended up looking like a fool. He has also hidden money from Charlie and once held off on telling Chelsea he was not Charlie when she snuggled next to him on the couch (she thought Charlie had fallen asleep there, but Charlie had forced Alan to give up the guest room and sleep in the TV room instead). Alan hit his low point when his above-board idea to solicit money from all his "family and Friends" in order to finance an ad campaign for his floundering chiropractic clinic slowly turned into a Ponzi Scheme. This encouraged him to let his dark side out, although he ended up giving everyone back their original investment and returning to square one.
Because of his cheapness, neurotic nature, and inept social skills, many find Alan annoying, even insufferable—-particularly Charlie, Evelyn, and Berta, who calls him "Zippy." On his 40th birthday, instead of saying nice things about him, everybody pointed out all his faults. Also, Jake seems to have little respect for him, though Jake is not particularly respectful of Charlie or Judith either, and is not generally rude when he talks to his dad. Though Evelyn has called him the good child, she added that Charlie had not set that bar very high. She also once seriously suggested he accept some prison time after an assault charge because she wanted to save money instead of using it to hire a lawyer. This leaves Alan with very few (If any) friends.
It is also implied that in the universe of the series that God himself has a dislike for Alan, for example when Charlie told Alan reminded him of Job, Alan shouts to the sky that he is not going to lose his faith only to start raining a few seconds later. The same thing happens in "Pie Hole, Herb" when Charlie refuses to take Alan back in (having kicked him out earlier), locking him out of house.
Alan is also seen as pitiful when he tries activities such as model car building and puppetry, because it highlights how anemic his social life is.
Alan drives a 2001 Volvo V70 station wagon (though he briefly owned a red Porsche Boxster in Season 2), runs his own chiropractic-care clinic in the San Fernando Valley, and gets irritated when people point out that he's not a "real" doctor. He lives in the guest room of Charlie's house, for which he paid no rent during his first 5 years, 2 months, and 11 days there because all his money went toward alimony and care of Jake. When Evelyn said she would pay for Jake's college education, Alan had no incentive to go to work and felt aimless. He then agreed to pay rent to Charlie every month, though the amount that would earn him a say in the household's operations was too high for him. Alan has also had to endure whatever inconvenience Charlie throws his way, and the fact that Charlie really, really wants him to move out permanently. Alan has also sometimes fantasized about killing Charlie in his sleep.
Alan is also a terrible liar, as proven in several episodes where he hastily creates a lie to get out of doing something, and Charlie always asks him for more detail to torture him and expose the lie.
Read more about this topic: Alan Harper (Two And A Half Men)