If some any hypothetical reason edo Itachi met Kisame during the fourth war, what would they talk about?

[[ This one is tricky, because by the time Itachi had been revived, Kisame was dead. Killer B already had Samehada in his possession and Naruto had been trained to utilize Kyuubi’s power.

But their meeting might not go over very well. Kisame was still working for “Madara”, and here is your ex-partner, who’s working against Madara.

Kisame certainly has a great deal of respect to Itachi, but he wouldn’t be pleased to know Itachi was working against him. It would just reaffirm that the world is full of liars, and would make his loyalty to Obito that much more permanent. 

The only other exception I could see where the situation is reversed is if someone told Kisame who “Madara” really was, but Itachi doesn’t know that, and no one actually figures it out (besides Kabuto), until the middle of the World War. ]]

Does Itachi even try to suppress the thing he has for his brother or does he let himself obsess freely as long as it’s just inside his head?

[[ He likes to keep inside his head. Anything that crosses the line between brothers is considered off-limits to him unless Sasuke initiates first, and then he tries to gently reject him because i think We Should Not Do That. 

But he’ll also cave with enough pressure. Anything he does show outwardly is an acceptable level of love. ]]