Homosexuality
Homosexuality is a sexual orientation. A homosexual person is romantically or sexually attracted to people of their own gender. Men who are romantically or sexually attracted to other men are called gay. Women who are romantically or sexually attracted to other women can be called gay as well, but are usually called lesbians. An example of a homosexual character would be Maxxie from skins. Maxxie is shown as being promiscuous throughout the series and is notably proud of being gay and feels no embarrassment or confuse meant towards his sexuality.
Heterosexual
this is simply opposite genders having a sexual attraction towards one or another. This orientation can then go on to represent there behaviours and how they fit in and are approached by within there community. An example of a heterosexual character would be cook from skins. Cook is renowned throughout the show as being very attracted and overly flirtatious towards many women and has numerous sexual encounters with females. Cook also uses homophobic language at points throughout the series indicating he is firmly heterosexual.

Bisexual
Bisexuality is when someone has sexual attractions to both men and women. This orientation can be reflected by both men and women and is becoming more common within todays society. And example of a bisexual character in tv drama would be piper from Orange is the new black. She has sexual encounters with both sexes during the series and is arguably confused about where she stands in terms of her sexual orientation.
Asexual
Asexual orientation is where the person has no sexual feelings towards either gender. This meaning they do not desire any romantic relationships. An example of this would be dexter him self in the program about him 'dexter'. He is a serial killer who shows little remorse or emotion through his executions which can be similarily linked to his lack of sexual emotion towards any other humans.