What were the circumstances when the Spirit bear appeared and stood watching Cole and Peter?

In the final chapter, Peter first proposes that he and Cole go soak in the freezing pond alone together. On the way, Peter starts pushing Cole after an angry dialogue. Cole refuses to fight back, which only makes Peter attack him harder—punching, kicking, and scratching Cole until he falls to the ground. Cole doesn’t do one thing to fight back. Upon seeing Cole so weak and laying hurt on the ground, Peter falls to his knees and starts crying. Just as Cole goes to hug him, the Spirit Bear appears. Peter is amazed and shocked that he appeared, and understands Cole’s concept of being “invisible.”