This is how I feel when I see this overused plot.

Okay so how it usually for is someone ( a main player in the game ex: daenerys ) has a twin. In the did it goes like five different yet unoriginal ways.

1; The oc takes the plot of the character whos twin they are.

2; The watch everything happen to that character

3; they're separated and across Westeros

4; they're Ned starks Ward

5; they don't know they have a twin and they have an amazing revelation.

Please do not use any of these. I have seen countless fics like this.

I mean some people can reallt pull it off with a unique storyline  but most cannot to be completely honest.

You can write a story like this if you wanna be really unoriginal and boring. There are few ways this plot can actually work