Good teammates know that some of the time, they’ll have to shoulder extra weight. The other teammate will be sick, or tired, or distracted, or in some other need.
Good teammates don’t complain when they have to carry their colleagues load. They don’t accuse, they don’t badmouth.
Good teammates know that there will come a time when someone will carry some of their weight.
Build a team of members who support each other, no matter what.