To fill the friendship meter, you must bring it corpses. The amount of friendship gained from a corpse is dependant on the corpses drag weight. For example, a managarmr with 250 drag weight will fill up the friendship meter by half, where as a yutyrannus with 500 drag weight will fully fill up the meter. (Note that this works with baby creatures) I’m fairly certain that the actual taming of the carch (killing creatures) is based on their health. So the more health a creature has, the more taming affinity it will reward. Hope this helps :)