I think they don't talk about it, they don't act on it, they maybe don't even realise they feel it, but they are each other's most stable and reliable connection, no backstabbing or politicking or pretense
even when they're angry with each other it feels like a relief. no secrets between them. lbh can safely let all his worst qualities be visible, no need to turn on the seductive charm. mbj can relax in the knowledge he's not being played by someone who pretends to care.
mbj will do whatever his lord requires of him. lbh will protect his trusted lieutenant.
any other feelings are unnecessary for them to analyse or pay attention to