Why I believe that Landon is Simulandon and Clarke is the Bone Warrior (by extension Landon is still in the prison world)
‘I Was Made To Love You’ is quite a big hint bc SL was made by Josie to get answers on their love triangle, in which he chose Hope right away. (all the Clarke flashbacks are no coincidence either)
Why does Landon have his memories of their first time but not fighting Ted? bc the last two times we actually saw Landon was in giving his body to Malivore and again when he wrote the letter. Meaning Hope and Perfect SL lost their virginities to each other. 
Cleo summoning a monster that brings the spirits of the dead was questioned from the beginning bc Landon wasn’t technically dead. but Simulandon did die in 2x08. (looking like Clarke but still simulandon’s body. Clarke “died” in 2x07)
1 of 2 outcomes could have happened when Clarke entered Simulandon’s body; one being Clarke gained SL abilities OR vise versa. I’m banking on Simulandon gaining Clarke’s bc we didn’t see SL having phoenix abilities during his episode but we know that Clarke is a gollum. A Gollum that under his human form resembles Malivore’s out-of-goo form??? So who’s to say that Clarke or in this case SL with Clarke’s abilities wouldn’t turn into goo when dead. -> Landon turning into goo at the end of 3x04. (Clarke literally told his father that he would be home for Christmas right before a redhood chopped his head off into a Malivore portal.)
I know that the bone whip and Hope’s “I felt like I fought them before” makes you think of Landon (especially after 1x01 and 3x05) but Landon used that bone whip ON Clarke. Plus she fought Clarke throughout 2x07.