Marmee Noir

He was sent there first, so maybe that planet is like skyring and several years have passed there. The other guy is alive, and as both of them are going to lose some memories, they are going to team up in order to survive together.

Fast forward several years, Clark and the gang arrive in Nakara and they have to face that monster alien spider. Bellamy saves them and since they can’t go back on their own, they have to stay there for a couple of years until the rest of the gang comes to rescue them, or Shepherd himself sends a retrieval team.

After years of being far away from Echo, and thinking they’re probably never coming back, Bellamy realizes that even if he loved Echo, Clarke has always been the one for him. They finally fall in love. 

Echo on the other hand, is not dealing well with Bellamy’s apparent death and she became unhinged and murderous. 

After all the groups are reunited, they will fight the disciples, Bellamy would have to face Echo and tell her about his feelings for Clark. For Echo the times hasn’t passed that much, maybe just a year since they were in Skyring. When they finally reunite both are changed and I hope, she already moved forward. If not she might be depressed after losing her lover and going back to being an assassin. Echo doesn’t make it on the end (I really, really hope not, because even if I’m a bellarke stan, I like Echo and I don’t want anything bad to happen to her, but after what we saw in the last episode, she might be on a “Finn” path...I don’t think Bell would have to kill her though, that would be horrible)