The Lion Timeline and Summary

Dorothy & Co. encounter the Lion on their way to Oz. At first it seems like he's going to attack, but he quickly admits that he's a coward.
The Lion decides to accompany the others to the Emerald City so he can ask the Wizard for some courage.
On the way to see Oz, the travelers encounter many hostile creatures and other challenges. The Lion shows bravery and strength on more than one occasion.
But he falls asleep in the field of poppies. His friends worry he'll die there until a team of field mice comes along and rescues him.
In Emerald City, the Lion asks Oz for courage. He's told he must help Dorothy kill the Wicked Witch of the West.
The gang heads west. The Lion is captured by the wicked witch, who puts him out in the yard to starve. Luckily, Dorothy sneaks him food.
The Lion is freed when Dorothy kills the witch. Time to head back to the Emerald City.
The Wizard gives the Lion some courage. It's just a placebo drink, but the Lion is pretty excited about it.
The Lion decides to accompany Dorothy on her journey to the South. When they pass through a forest, he kills a giant spider and becomes king.
He continues with Dorothy to see Glinda the Good Witch. Glinda promises him a ride back to the forest so he can begin his new life as king.