Meredith is the Human version of his Demon brother! That's why he can't leave the tower and Meredith is the one who live along side the human!! because he want to protect them ! And I think The human version of his Demon Brother which is ( Meredith ) forgot What he need to do!! Thats why Rood told him at the end you "were not able to achieved anything"!! Thats why he asked him if HE STILL WANT TO PROTECT THEM? ( While having a Shocked Look) when Rood asked it to him. ( Because if you can see Rood literally asked him as if he is the demon brother)
And I think it is the reason why Lispen is not fond of that Demon brother of Rood!! because he actually sacrifice himself just to protect the human not just protect but he actually live with them which is (Meredith)!! now it become more clearer why he is so clingy to Rood
If you can see LISPEN used the word (BELOW) literally means (underneath) and all of us knew that the one BELOW is the (CHAINED DEMON KING) but Lispen showed the image of (MEREDITH) instead the (CHAINED DEMON KING)