Science fiction is a genre, whose stories take place in an imaginary environment where science, and in particular the technological development has undergone more or less significant changes with effect on both society and individuals. Science fiction is based on more or less imaginative themes of science results and ways of looking. The topics are often about high tech future societies, space travels, time travels, creatures, end of world, different universes etc. 
The short story takes place in the future where the technology has taken over, and where people can buy their happiness for money, and that human now just can go to a rental shop and get a new heart in order to avoid pain When you fall in love, often you will get or end up with a broken heart. It happens for almost every one, who gets in relations with other people. But in this short story, you can get out and rent a new heart, and meet other relations without having any fear of getting hurt. The short story is about a person that has been in love with a lot of people, and then tries to not getting hurt.
When he/she is getting hurt by the relations she/he goes through, he/she keeps going to the “rental place”, every time he/she falls in love, so instead of dealing with some of the pain and letting it get worse, he/she just visit the rental place and rent a new heart. There is no information or any descriptions about the main characters sex, but I would say that it is a teenage boy because he does not appear to be dramatically, and does not describe the actions detailed, as a girl would do generally.
The main character is a teenager, since a typical teenager would say “And our love was going to last forever, which at our age meant six months. ” It starts with his first love with Jacob, where he was very much in love with him, and they were happy for each other. “… first heart. Jacob was as solid and golden as a tilled field, and our love was going to last forever, which at our age meant six months. Every time Jacob touched me, I felt my heart thud wetly against my lungs. But in the last, Jacob left him which broke his heart. . A year later he meets Anna, who is a girl. She tells him to go and rent a heart so he may be able to fall in love, because he is afraid to fall in love, since his heart has been broken before. Renting hearts made him not to feel any pain again, because of this opportunity to rent a heart. Teenagers are often confused, and a lot of things don’t make sense, especially love and relations.
They fall in love quickly, and as they fall in love, they can easily fall off again. Throughout the short story, he meets both men and women, which says that he is bisexual. It may also be quite normal in this society, in the future, where you in fact can simply buy a new heart, where it is possible to try anything without noticing any consequences, otherwise it may be because he is confused about his own sex and therefore he is trying to figure out his relations to both men and women.
The main character seems to have it difficult to find a balance in his life, because he cannot live without being with a regular partner, or without having someone who loves him. He cannot even manage to break up with a partner, and naturally calm down, and it is pretty hard for him, where he will feel sorrow for a long time, which he cannot stand, and therefor has to switch his mechanic heart, to get in better conditions and save himself from the pain.
Another problem with the main character is that he cannot incorporate his feelings, especially with regards to be an open person towards his relations properly. He fall in love, without looking for his partners criteria, and even don’t find out if the partner matches his expectations, but will instead end up in relation without any feelings and without any fear of falling in love and get hurt.
I don’t think that he lives under a safe environment with values such as family, friends or work, or a stable structure. That is what I assume. He is actually locking himself out of the truth, and he knows that his actions are wrong, so he make himself renting hearts as a facade but is still feeling bad about his life because everyone who rent a heart will realize that pain isn’t just in the heart, but also in the mind, and it cannot be obviated.