I echo fireflybob and aerostudent
It definetly is the person who you share the flightdeck with who can make your day. It's a good feeling to walk in to the crewroom, look at the sign in and see someone who you respect and get on with. Makes all the other sh1t go smoothly and even if it doesn't, it won't spoil the day..you deal with it together.
Unfortunately, on the other hand, there is always some **** that is intent to drag you down to their level of negativity. Thankfully they aren't that plentiful.