To ensure automatic loading in media players (Plex, Jellyfin, MPC-HC, VLC), rename your .srt subtitle file to match the video file exactly, with the language code.
Game of Thrones is unique because it requires specific subtitle handling for its fictional languages: Forced Subtitles: These only appear when characters speak High Valyrian Game.of.thrones.season.4.720p.bluray.x264-shaanig Subtitles