It depends what you mean by teenagers and what you mean by smut.
16-year-olds having sex with other 16-year-olds is fine.
13-year-olds being violently raped by adults, on the other hand... yeah, in theory, fiction =/= reality, but in practice everyone I've ever met who's been into stuff like this has been awkward and creepy.
There's also a difference between a teenage character in a show geared at teens or adults and a teenage (or even younger) character from a show geared towards small children. Most people I've met who've been into smut with characters from shows for really young children have been weird, too.
no subject
16-year-olds having sex with other 16-year-olds is fine.
13-year-olds being violently raped by adults, on the other hand... yeah, in theory, fiction =/= reality, but in practice everyone I've ever met who's been into stuff like this has been awkward and creepy.
There's also a difference between a teenage character in a show geared at teens or adults and a teenage (or even younger) character from a show geared towards small children. Most people I've met who've been into smut with characters from shows for really young children have been weird, too.