Merlin and Fou

Many people seem to think that Fou (Cath Palug) hates Merlin but I think that was just at the beginning and also for comic relief. Fou loved staying in Avalon but Merlin kicked him out of the Tower so that - in his words - Fou can go "to experience all the beauty this world has to offer". It was for Fou's own good, and later Fou does acknowledge that it helped him grow and prevented him from becoming Beast IV. Also, they have always been bickering since the beginning (like Disney's Merlin and Archimedes' dynamics). 

I 90% agree with this post so I'm copying it here:  

While Cath Palug smacking Merlin is a running gag throughout the singularity, I get the feeling that, while in the beginning he hated him (for kicking him out of the Tower), Merlin eventually grew on him, not that Cath Palug is about to admit it.

Cath Palug pushes Merlin to go to sleep, and while the smacking seems like a joke, Cath Palug had interrupted Merlin while he was being uncharacteristically depressing. Whether Merlin sees it as him caring or him simply hitting him is honestly nebulous; Merlin IS highly intelligent even if he acts like a moron. Whether he has the capacity to understand that Cath Palug cares much for him is up for debate.

Much later, when you talk to Merlin, just as Merlin’s being Merlin and bullshitting you, Cath Palug smacks him again and pretty much tells him to open up to you. Because Cock Wizard needs friends.

So as abrasive as Cath Palug is to Merlin, I do think he genuinely cares about him.