Bellamy and Clarke are a solid team. It seems that no matter what either of them do, the other is always there to offer forgiveness and understanding when it's needed. Both understand the harsh realities of doing whatever is necessary in order to survive.
Bellamy did many terrible and inexcusable things in The 100 Season 3. Hopefully, Season 4 won't sweep those under the rug, but will allow him to confront his past mistakes, atone for them, and finally move on.
Kane was at his lowest point when we last saw him during The 100 Season 3 Finale. Will he be able to reconcile the things he did and said while under ALIE's control and be an effective leader of his people once again?
Here, Jaha is in the middle of some kind of tense standoff between Grounders and Sky People. What's going on in Polis? Lexa was able to enjoy a peaceful reign for some amount of time -- will the next Commander be able to re-establish peace among the clans?
Jaha was instrumental in releasing ALIE and setting off her reign of terror. How will he assimilate among the Sky People in the aftermath of all of the pain he unwittingly caused under the AI's control?
Abby, Kane, Bellamy, and Clarke are clearly still in Polis during the season premiere. After spending most of Season 3 separated, will this group be able to go back to working together to save everyone from ALIE's predicted nuclear annihilation?
Lexa: My fight is over. Clarke: No, I won't accept that. Lexa: You were right, Clarke. Life is about more than just surviving. Clarke: In peace may you leave the shore. In love may you find the next. Safe passage on your travels until our final journey on the ground... May we meet again.