Someone above said you are put with the fastpass people and if you're with someone you could sit together - that isn't technically right. You enter where the fastpass people do and are given a single rider pass than part of the way up the line the single rider people go one way and the fastpass go a different way. We did single rider a few times the end of May and we never got seated together, sometimes 2 of us were on the same train. If you get there at rope drop just do Standby and grab a fastpass for later. If you arriver later in the day then single rider is a good alternative for a minimal wait, especially if fastpasses are gone. We did find that at the end of the day, like last hour of park, there was hardly any wait standby so they didn't do single rider.