DA Although I feel like I should mention about Legends of Tomorrow, just in case OP (like me) is a bit of a canon completist: Sara, the bi character, first shows up on s2 of Arrow, which is a fairly het show (Sara's ex-girlfriend shows up so it's not f/f free, but Sara does spend a good part of the season in a het relationship with the main protagonist). Legends of Tomorrow is pretty easy to follow without watching any of the other DC shows, though! But if you like to get all the backstory for your fave, you might need to wade through some het for it (and also might end up watching about four different shows if you want all the backstory for everyone /currently trying to resist getting drawn into the other Arrowverse shows because that is just too much TV to keep up with)