In this book Magnus uses his friends to help him defeat loki in a flyting. He has his friends to support him during this trial.
In the lightning thief, Percy and Grover prove their friendship by sticking with each other even through the bullying of Nancy.
IN the end they use their friendship to save the day. They loved each other as friends enough to get through their trial.
In twilights kingdom part 2, Tirek threatens twilight with her friends. She accepts this and her friends are freed. She lost her magic, but with the support of her friends, she gets it back and defeats tirek.
IN alone together, steven and connie support each other when fused into stevonnie. They then unfuse and all of their worries disapear. This represents that friendship helps us through trials
In goin fishin, he has his friends supporting him. In Blendins game, Soos has his friends support him. This supports the theme that friends help you through trials.