Octopus: You mean he's... like... a vegetable now?
Mantis: I think more accurately, he's like an animal now.
Octopus: Don't be a dick, man, Berthold was one of us!
Mantis: He's not dead. And given what happened to him that's fucking amazing. And the person it'd make the most difference to won't know the difference. Be happy for Wolf.
Sniper Wolf giving Liquid the dog tags of his "father" after he regained his body.
Coming from the two most otherwise despicable members of the group, Ocelot and Mantis' genuine offer of companionship to The Sorrow and offer of their library is surprisingly heartwarming, especially Ocelot point that Sorrow is no weirder than any of the others and could belong with them. It's particularly interesting for the offer to come from Ocelot, as The Sorrow is a being he has no possible means of controlling (and who could have easily known things that might have been detrimental to his plans), and for Mantis - who would usually rather kill people than connect with them - to jump in to help convince him.
Double heartwarming considering the Sorrow is Ocelot's father.
In the later chapters, after Sniper Wolf's brain checks out to lunch due to sleep deprivation, she heads to Russia to assassinate Sergei Gurlukovich. Ocelot makes the slightest suggestion that they let the Russians handle tracking her down, which they would do lethally. Liquid grabs Ocelot by the collar and gets in his face!
Liquid:: We don't play that game. Understand me? Not ever?
The scene where Psycho Mantis and Revolver Ocelot are trying to replicate the scene years ago when Ocelot was playing Russian Roulette by juggling three loaded guns, and The Boss grabs the last gun and fires it. Both of them are trying to find which gun would go off, to no avail. It's pretty funny, but the heartwarming part is that despite being mortal enemies, Mantis and Ocelot still were willing to sit down and work together to solve the problem.