Having worked together in the past makes sesne! Giovanni's obedience to the Company is absolute so yeah, whilst he's under no illusions about them being good or just and has a vague sense of bleakness towards his lot in life, his obedience never waivers. And while he's never exactly 'friendly', he at least maintains a vaneer of politeness towards anyone he feels is deserving of it (which gets stronger and more subservient the higher they are above him in the Company).

He's more inclined towards sly, snarky banter with anyone whom he thinks he can get away with it, so if their positions are similar there'll probably be some of that, ahah. Also he'd be a bit more relaxed around someone he isn't working underneath, so there's that!